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Search for "proline" in Full Text gives 191 result(s) in Beilstein Journal of Organic Chemistry.
An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals
- Marcus Baumann,
- Ian R. Baxendale,
- Steven V. Ley and
- Nikzad Nikbin
Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57
- chloride 89 are added concurrently from two different sides of the reactor to stop these reagents reacting with each other. This method of adding the reagents circumvents the necessity to isolate the magnesium salt of the indole and increases the yield from 50 to 82%. The carbonyl group of the proline side
Graphical Abstract
Figure 1: Structures of atorvastatin and other commercial statins.
Figure 2: Structure of compactin.
Scheme 1: Synthesis of pentasubstituted pyrroles.
Scheme 2: [3 + 2] Cycloaddition to prepare 5-isopropylpyrroles.
Scheme 3: Regiospecific [3 + 2] cycloaddition to prepare the pyrrole scaffold.
Scheme 4: Formation of the pyrrole core of atorvastatin via [3 + 2] cycloaddition.
Scheme 5: Formation of pyrrole 33 via the Paal–Knorr reaction.
Scheme 6: Convergent synthesis towards atorvastatin.
Figure 3: Binding pocket of sunitinib in the TRK KIT.
Scheme 7: Synthesis of sunitinib.
Scheme 8: Alternative synthesis of sunitinib.
Scheme 9: Key steps in the syntheses of sumatriptan and zolmitriptan.
Scheme 10: Introduction of the N,N-dimethylaminoethyl side chain.
Scheme 11: Japp–Klingemann reaction in the synthesis of sumatriptan.
Scheme 12: Synthesis of the intermediate sulfonyl chlorides 62 and 63.
Scheme 13: Alternative introduction of the sulfonamide.
Scheme 14: Negishi-type coupling to benzylic sulfonamides.
Scheme 15: Heck reaction used to introduce the sulfonamide side chain of naratriptan.
Scheme 16: Synthesis of the oxazolinone appendage of zolmitriptan.
Scheme 17: Grandberg indole synthesis used in the preparation of rizatriptan.
Scheme 18: Improved synthesis of rizatriptan.
Scheme 19: Larock-type synthesis of rizatriptan.
Scheme 20: Synthesis of eletriptan.
Scheme 21: Heck coupling for the indole system in eletriptan.
Scheme 22: Attempted Fischer indole synthesis of elatriptan.
Scheme 23: Successful Fischer indole synthesis for eletriptan.
Scheme 24: Mechanistic rationale for the Bischler–Möhlau reaction.
Scheme 25: Bischler-type indole synthesis used in the fluvastatin sodium synthesis.
Scheme 26: Palladium-mediated synthesis of ondansetron.
Scheme 27: Fischer indole synthesis of ondansetron.
Scheme 28: Optimised Pictet–Spengler reaction towards tadalafil.
Figure 4: Structures of carvedilol 136 and propranolol 137.
Scheme 29: Synthesis of the carbazole core of carvedilol.
Scheme 30: Alternative syntheses of 4-hydroxy-9H-carbazole.
Scheme 31: Convergent synthesis of etodolac.
Scheme 32: Alternative synthesis of etodolac.
Figure 5: Structures of imidazole-containing drugs.
Scheme 33: Synthesis of functionalised imidazoles towards losartan.
Scheme 34: Direct synthesis of the chlorinated imidazole in losartan.
Scheme 35: Synthesis of trisubstituted imidazoles.
Scheme 36: Preparation of the imidazole ring in olmesartan.
Scheme 37: Synthesis of ondansetron.
Scheme 38: Alternative route to ondansetron and its analogues.
Scheme 39: Proton pump inhibitors and synthesis of esomeprazole.
Scheme 40: Synthesis of benzimidazole core pantoprazole.
Figure 6: Structure of rabeprazole 194.
Scheme 41: Synthesis of candesartan.
Scheme 42: Alternative access to the candesartan key intermediate 216.
Scheme 43: .Medicinal chemistry route to telmisartan.
Scheme 44: Improved synthesis of telmisartan.
Scheme 45: Synthesis of zolpidem.
Scheme 46: Copper-catalysed 3-component coupling towards zolpidem.
Figure 7: Structure of celecoxib.
Scheme 47: Preparation of celecoxib.
Scheme 48: Alternative synthesis of celecoxib.
Scheme 49: Regioselective access to celecoxib.
Scheme 50: Synthesis of pazopanib.
Scheme 51: Syntheses of anastrozole, rizatriptan and letrozole.
Scheme 52: Regioselective synthesis of anastrozole.
Scheme 53: Triazine-mediated triazole formation towards anastrozole.
Scheme 54: Alternative routes to 1,2,4-triazoles.
Scheme 55: Initial synthetic route to sitagliptin.
Figure 8: Binding of sitagliptin within DPP-IV.
Scheme 56: The process route to sitagliptin key intermediate 280.
Scheme 57: Synthesis of maraviroc.
Scheme 58: Synthesis of alprazolam.
Scheme 59: The use of N-nitrosoamidine derivatives in the preparation of fused benzodiazepines.
Figure 9: Structures of itraconazole, ravuconazole and voriconazole.
Scheme 60: Synthesis of itraconazole.
Scheme 61: Synthesis of rufinamide.
Scheme 62: Representative tetrazole formation in valsartan.
Figure 10: Structure of tetrazole containing olmesartan, candesartan and irbesartan.
Scheme 63: Early stage introduction of the tetrazole in losartan.
Scheme 64: Synthesis of cilostazol.
Figure 11: Structure of cefdinir.
Scheme 65: Semi-synthesis of cefdinir.
Scheme 66: Thiazole syntheses towards ritonavir.
Scheme 67: Synthesis towards pramipexole.
Scheme 68: Alternative route to pramipexole.
Scheme 69: Synthesis of famotidine.
Scheme 70: Efficient synthesis of the hyperuricemic febuxostat.
Scheme 71: Synthesis of ziprasidone.
Figure 12: Structure of mometasone.
Scheme 72: Industrial access to 2-furoic acid present in mometasone.
Scheme 73: Synthesis of ranitidine from furfuryl alcohol.
Scheme 74: Synthesis of nitrofurantoin.
Scheme 75: Synthesis of benzofuran.
Scheme 76: Synthesis of amiodarone.
Scheme 77: Synthesis of raloxifene.
Scheme 78: Alternative access to the benzo[b]thiophene core of raloxifene.
Scheme 79: Gewald reaction in the synthesis of olanzapine.
Scheme 80: Alternative synthesis of olanzapine.
Figure 13: Access to simple thiophene-containing drugs.
Scheme 81: Synthesis of clopidogrel.
Scheme 82: Pictet–Spengler reaction in the preparation of tetrahydrothieno[3,2-c]pyridine (422).
Scheme 83: Alternative synthesis of key intermediate 422.
Figure 14: Co-crystal structures of timolol (left) and carazolol (right) in the β-adrenergic receptor.
Scheme 84: Synthesis of timolol.
Scheme 85: Synthesis of tizanidine 440.
Scheme 86: Synthesis of leflunomide.
Scheme 87: Synthesis of sulfamethoxazole.
Scheme 88: Synthesis of risperidone.
Figure 15: Relative abundance of selected transformations.
Figure 16: The abundance of heterocycles within top 200 drugs (5-membered rings).
Effects of anion complexation on the photoreactivity of bisureido- and bisthioureido-substituted dibenzobarrelene derivatives
- Heiko Ihmels and
- Jia Luo
Beilstein J. Org. Chem. 2011, 7, 278–289, doi:10.3762/bjoc.7.37
- dibenzobarrelene derivative 1c which forms the chiral ammonium carboxylate 1c-P with (S)-proline (Scheme 2). After irradiation, acidic workup and subsequent esterification with diazomethane, the dibenzosemibullvalene 2c was obtained with high enantiomeric excess (>95% ee) [35][36]. Interestingly, several
Graphical Abstract
Scheme 1: Photorearrangements of dibenzobarrelenes 1a and 1b.
Scheme 2: Stereoselective DPM rearrangement of chiral salts in the solid-state.
Scheme 3: Synthesis of ureido- and thioureido-substituted dibenzobarrelene derivatives 1e–i.
Scheme 4: Di-π-methane rearrangements of ureido- and thioureido-substituted dibenzobarrelene derivatives 1h a...
Figure 1: Photometric titration of A) tetrabutylammonium chloride (TBAC) to 1h (c1h = 50 µM) and of B) tetrab...
Figure 2: Structures of chiral additives employed in DPM rearrangements.
Figure 3: Structure of anthracene–thiourea conjugate 4.
Figure 4: Proposed structure of the complex between 1h and mandelate SMD.
Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds
- Carolin Fischer and
- Burkhard Koenig
Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10
- bromide affected the yield only marginally [63]. A second example of intramolecular coupling is the synthesis of promazine drugs (56) that are interesting due to their clinical use for psychotropic medication. The CuI/L-proline-catalysed cascade process, developed by Ma et al., gave the best yields when 2
- , reaction temperatures (90–115 °C) and reaction times (48 h) are comparable to the palladium-catalysed processes. Ligand-free and ligand-assisted reaction conditions have been applied in the synthesis of biologically active compounds. DMEDA, proline and phenanthroline are the most commonly used ligands. In
Graphical Abstract
Scheme 1: Synthesis of selective D3 receptor ligands.
Scheme 2: Synthesis of a novel 5-HT1B receptor antagonist.
Scheme 3: Synthesis of A-366833, a selective α4β2 neural nicotinic receptor agonist.
Scheme 4: A new route to oxcarbazepine.
Scheme 5: Synthesis of key intermediates for norepinephrine transporter (NET) inhibitors.
Scheme 6: N-Annulation yielding substituted indole for the synthesis of demethylasterriquinone A1.
Scheme 7: Palladium-catalysed double N-arylation contributing to the synthesis of murrazoline.
Scheme 8: Synthesis of vitamin E amines.
Scheme 9: Improved synthesis of martinellic acid.
Scheme 10: New tariquidar-derived ABCB1 inhibitors.
Scheme 11: β-Carbolin-1-ones as inhibitors of tumour cell proliferation.
Scheme 12: Copper-catalysed synthesis of promazine drugs.
Scheme 13: Palladium-catalysed multicomponent reaction for the synthesis of promazine drugs.
Scheme 14: Key intermediate for imatinib.
Scheme 15: Synthesis of an effective Chek1/KDR kinase inhibitor.
Scheme 16: Macrocyclization as final step of the synthesis of heat shock protein inhibitor.
Scheme 17: Synthesis of N-arylimidazoles.
Scheme 18: Synthesis of benzolactam V8.
Scheme 19: Synthesis of an intermediate for lotrafiban (SB-214857).
Scheme 20: Intermolecular effort towards lotrafiban.
Scheme 21: Synthesis of matrix metalloproteases (MMPs) inhibitor.
Scheme 22: Regioselective 9-N-arylation of purines.
Scheme 23: N-Arylation of adenine and cytosine.
Scheme 24: 9-N-Arylpurines as enterovirus inhibitors.
Scheme 25: Xanthine analogues as kinase inhibitors.
Scheme 26: Synthesis of dual PPARα/γ agonists.
Scheme 27: N-Aryltriazole ribonucleosides with anti-proliferative activity.
Surfactant catalyzed convenient and greener synthesis of tetrahydrobenzo[a]xanthene-11-ones at ambient temperature
- Pravin V. Shinde,
- Amol H. Kategaonkar,
- Bapurao B. Shingate and
- Murlidhar S. Shingare
Beilstein J. Org. Chem. 2011, 7, 53–58, doi:10.3762/bjoc.7.9
- , synthetic methods that involve tetra(n-butyl)ammonium fluoride (TBAF) [25] and proline triflate [26] in water have been described. However, the major problems associated with these routes are the need for higher/reflux conditions and longer reaction times. Therefore, it was thought worthwhile to develop a
Graphical Abstract
Scheme 1: Standard model reaction.
Figure 1: Optical micrograph of the reaction mixture. (A) normal view, (B) magnified view. (Scale bar = 2.5 µ...
Figure 2: Schematic diagram representing the role of TTAB.
Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt
- Kumaresh Ghosh,
- Tanmay Sarkar and
- Asoke P. Chattopadhyay
Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139
- excited state of anthracene is regulated in different ways. We presume that receptor 1 may follow any equilibrium-binding mode A, B or C with valine, alanine and phenylglycine salts in solution as shown in Figure 5. This is also true for the mandelate, pyruvate and proline salts. Relevance of the
Graphical Abstract
Figure 1: Synthesized compounds 1 and 2.
Scheme 1: Syntheses of 1 and 2.
Figure 2: Change in 1H NMR of (A) 1 (400 MHz, CDCl3 containing 0.4% d6-DMSO; c = 2.80 × 10−3 M) and in the pr...
Figure 3: Change in fluorescence ratio of 1 upon addition of one equivalent of anions (c = 4.31 × 10−5 M) at ...
Figure 4: Change in emission of 1 (c = 4.31 × 10−5 M) upon gradual addition of tetrabutylammonium salts of (a...
Figure 5: Suggested modes of binding of the amino acid salts into the open cleft of 1.
Figure 6: Fluorescence titration curves for 1 (c = 4.31 × 10−5 M) at 492 nm.
Figure 7: Fluorescence decays (at λmax = 420 nm) of receptor 1 upon the addition of 1 equiv of L-N-acetylvali...
Figure 8: Change in absorbance of 1 (c = 4.31 × 10−5 M) upon gradual addition of tetrabutylammonium salts of ...
Figure 9: DFT optimized geometry of the complex of 1 with L-N-acetylvaline carboxylate salt [a = 1.93 Å, b = ...
Synthesis of a novel analogue of DPP-4 inhibitor Alogliptin: Introduction of a spirocyclic moiety on the piperidine ring
- Arumugam Kodimuthali,
- Padala Lakshmi Prasunamba and
- Manojit Pal
Beilstein J. Org. Chem. 2010, 6, No. 71, doi:10.3762/bjoc.6.71
- dipeptidyl peptidase-4 (DPP-4; CD26; E.C. 3.4.14.5) by small molecules has emerged as one of the key approaches for the treatment of type-2 diabetes [1][2][3][4][5]. DPP-4, a member of the prolyl oligopeptidase family of serine protease, cleaves the N-terminal dipeptide from peptides with proline or alanine
Graphical Abstract
Figure 1: Design of a new DPP-4 inhibitor (C) based on Alogliptin (A) and other inhibitors (B).
Figure 2: Strategy to prepare compound C (PG = protecting group).
Scheme 1: Reagents and conditions: (i) EtONa, BrCH2CH2Br, EtOH, reflux, 3.5 h (70% yield); (ii) Pd/C, MeOH, H2...
Scheme 2: Reagents and conditions: (i) NaH, LiBr, DMF - DMSO, 12 h (55% yield); (ii) NaH, LiBr, CH3I, DMF - T...
Figure 3: Predicted interactions of compound C with DPP-4.
Synthesis of glycosylated β3-homo-threonine conjugates for mucin-like glycopeptide antigen analogues
- Florian Karch and
- Anja Hoffmann-Röder
Beilstein J. Org. Chem. 2010, 6, No. 47, doi:10.3762/bjoc.6.47
- pseudo-glycopeptide was assembled in an automated synthesiser by the Fmoc-strategy on a TentaGel S resin 5 equipped with a bulky trityl linker [38] to avoid diketopiperazine formation and pre-loaded with Fmoc-proline (Scheme 2). The first 13 amino acids of the MUC1 sequence were coupled under standard
- -L-valyl-O-[α-3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-galactopyranosyl]-homo-β3-threonyl-L-seryl-L-alanyl-L-prolyl-L-aspartyl-L-threonyl-L-arginyl-L-prolyl-L-alanyl-L-prolyl-L-glycyl-L-seryl-L-threonyl-L-alanyl-L-proline 7: The synthesis was carried out in an Applied Biosystems ABI 433A peptide
- -L-alanyl-L-prolyl-L-glycyl-L-seryl-L-threonyl-L-alanyl-L-proline 8: Peptide 7 was dissolved in 10 mL of methanol (HPLC grade). A fresh solution of sodium methanolate in methanol (0.5 g Na in 25 mL methanol (HPLC grade)) was added drop wise until pH 9.5 was reached. The reaction mixture was stirred
Graphical Abstract
Figure 1: Structures of the naturally occurring TN and TF antigens and the targeted Fmoc-β3hThr analogues.
Scheme 1: Synthesis of Fmoc-β3hThr antigen conjugates by Arndt–Eistert homologation.
Scheme 2: Solid-phase synthesis of the tumour-associated MUC1 α/β-hybrid glycopeptide analogue 8 carrying the...
The C–F bond as a conformational tool in organic and biological chemistry
- Luke Hunter
Beilstein J. Org. Chem. 2010, 6, No. 38, doi:10.3762/bjoc.6.38
- enantioselectivity suggesting that the fluorine atom of 35 helps to rigidify the activated intermediate and thereby enhances selectivity. Another fluorinated organocatalyst has recently featured in the first example of an asymmetric transannular aldol reaction (Figure 10) [35]. (S)-proline (39) is able to catalyse
- Cγ-exo proline ring shape, reinforced by the F–C–C–N gauche effect, could be partly responsible for the high enantioselectivity of catalyst 41. As an illustration of the importance of this work, catalyst 41 has already been put to good use in a total synthesis of the natural product (+)-hirsutine (46
- is often proline (39) and Yaa is often 4(R)-hydroxyproline (63). The triple helix is partly held together by backbone hydrogen bonds and for many years it was thought that the hydroxyl groups of the 4(R)-hydroxyproline residues (63) contributed to the stability of collagen by providing extra hydrogen
Graphical Abstract
Figure 1: Conformational effects associated with C–F bonds.
Figure 2: HIV protease inhibitor Indinavir (17) and fluorinated analogues 18 and 19. In analogue 18 the gauche...
Figure 3: Cholesteryl ester transfer protein inhibitors 20 and 21. In the fluorinated analogue 21, nO→σ*CF hy...
Figure 4: HIV reverse transcriptase inhibitor 22 and acid-stable fluorinated analogues 23–25. The F–C–C–O gau...
Figure 5: Dihydroquinidine (26) and fluorinated analogues 27 and 28. Newman projections along the C9–C8 bonds...
Figure 6: The neurotransmitter GABA (29) and fluorinated analogues (R)-30 and (S)-30. Newman projections of (R...
Figure 7: The insect pheromone 31 and fluorinated analogues (S)-32 and (R)-32. The proposed bioactive conform...
Figure 8: Capsaicin (33) and fluorinated analogues (R)-34 and (S)-34.
Figure 9: Asymmetric epoxidation reaction catalysed by pyrrolidine 35. Inset: the geometry of the activated i...
Figure 10: The asymmetric transannular aldol reaction catalysed by trans-4-fluoroproline (41), and its applica...
Figure 11: The asymmetric Stetter reaction catalysed by chiral NHC catalysts 49–52. The ring conformations of ...
Figure 12: A multi-vicinal fluoroalkane.
Figure 13: X-ray crystal structures of diastereoisomeric multi-vicinal fluoroalkanes 55 and 56. The different ...
Figure 14: Examples of fluorinated liquid crystal molecules. Arrows indicate the orientation of the molecular ...
Figure 15: Di-, tri- and tetra-fluoro liquid crystal molecules 60–62.
Figure 16: Collagen mimics of general formula (Pro-Yaa-Gly)10 where Yaa is either 4(R)-hydroxyproline (63) or ...
Figure 17: Enkephalin-related peptide 64 and the fluorinated analogue 65. The electron-withdrawing trifluorome...
Figure 18: The C–F bond influences the conformation of β-peptides. β-Heptapeptide 66 adopts a helical conforma...
Figure 19: The conformations of pseudopeptides 69 and 70 are influenced by the α-fluoroamide effect and the fl...
C-Arylation reactions catalyzed by CuO-nanoparticles under ligand free conditions
- Mazaahir Kidwai,
- Saurav Bhardwaj and
- Roona Poddar
Beilstein J. Org. Chem. 2010, 6, No. 35, doi:10.3762/bjoc.6.35
- of attention has been focused on the development of Pd catalyzed arylation [8][9][10][11]. Another important protocol involves arylation of activated methylene compounds mediated by copper salts [12][13]. Recently, proline has also been used along with CuI for C-arylation [14]. But some of the
Graphical Abstract
Scheme 1: Synthesis of 3-phenylpentane-2,4-dione using CuO-nanoparticles.
Figure 1: Powder X-ray diffraction pattern and TEM image of nano CuO (fresh).
Scheme 2: Synthesis of 3-phenylpentane-2,4-dione using CuO-nanoparticles.
Scheme 3: Synthesis of diethyl 2-aryl-malonate using CuO-nanoparticles.
Figure 2: Proposed reaction pathway for the CuO-nanoparticles catalyzed C–C coupling reaction.
Figure 3: Powder X-ray diffraction pattern and TEM image of recycled CuO-nanoparticles.
Molecular recognition of organic ammonium ions in solution using synthetic receptors
- Andreas Späth and
- Burkhard König
Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32
Graphical Abstract
Figure 1: Biologically important amines and quaternary ammonium salts: histamine (1), dopamine (2) and acetyl...
Figure 2: Crown ether 18-crown-6.
Figure 3: Conformations of 18-crown-6 (4) in solvents of different polarity.
Figure 4: Binding topologies of the ammonium ion depending on the crown ring size.
Figure 5: A “pseudorotaxane” structure consisting of 24-crown-8 and a secondary ammonium ion (5); R = Ph.
Figure 6: Typical examples of azacrown ethers, cryptands and related aza macrocycles.
Figure 7: Binding of ammonium to azacrown ethers and cryptands [111-113].
Figure 8: A 19-crown-6-ether with decalino blocking groups (11) and a thiazole-dibenzo-18-crown-6-ether (12).
Figure 9: 1,3-Bis(6-oxopyridazin-1-yl)propane derivatives 13 and 14 by Campayo et al.
Figure 10: Fluorescent azacrown-PET-sensors based on coumarin.
Figure 11: Two different pyridino-cryptands (17 and 18) compared to a pyridino-crown (19); chiral ammonium ion...
Figure 12: Pyridino-18-crown-6 ligand (21), a similar acridino-18-crown-6 ligand (22) and a structurally relat...
Figure 13: Ciral pyridine-azacrown ether receptors 24.
Figure 14: Chiral 15-crown-5 receptors 26 and an analogue 18-crown-6 ligand 27 derived from amino alcohols.
Figure 15: C2-symmetric chiral 18-crown-6 amino alcohol derivatives 28 and related macrocycles.
Figure 16: Macrocycles with diamide-diester groups (30).
Figure 17: C2-symmetric chiral aza-18-crown-6 ethers (31) with phenethylamine residues.
Figure 18: Chiral C-pivot p-methoxy-phenoxy-lariat ethers.
Figure 19: Chiral lariat crown ether 34.
Figure 20: Sucrose-based chiral crown ether receptors 36.
Figure 21: Permethylated fructooligosaccharide 37 showing induced-fit chiral recognition.
Figure 22: Biphenanthryl-18-crown-6 derivative 38.
Figure 23: Chiral lariat crown ethers derived from binol by Fuji et al.
Figure 24: Chiral phenolic crown ether 41 with “aryl chiral barriers” and guest amines.
Figure 25: Chiral bis-crown receptor 43 with a meso-ternaphthalene backbone.
Figure 26: Chromogenic pH-dependent bis-crown chemosensor 44 for diamines.
Figure 27: Triamine guests for binding to receptor 44.
Figure 28: Chiral bis-crown phenolphthalein chemosensors 46.
Figure 29: Crown ether amino acid 47.
Figure 30: Luminescent receptor 48 for bis-alkylammonium guests.
Figure 31: Luminescent CEAA (49a), a bis-CEAA receptor for amino acids (49b) and the structure of lysine bindi...
Figure 32: Luminescent CEAA tripeptide for binding small peptides.
Figure 33: Bis crown ether 51a self assembles co-operatively with C60-ammonium ion 51b.
Figure 34: Triptycene-based macrotricyclic dibenzo-[24]-crown-8 ether host 52 and guests.
Figure 35: Copper imido diacetic acid azacrown receptor 53a and the suggested His-Lys binding motif; a copper ...
Figure 36: Urea (54) and thiourea (55) benzo crown receptor for transport and extraction of amino acids.
Figure 37: Crown pyryliums ion receptors 56 for amino acids.
Figure 38: Ditopic sulfonamide bridged crown ether receptor 57.
Figure 39: Luminescent peptide receptor 58.
Figure 40: Luminescent receptor 59 for the detection of D-glucosamine hydrochloride in water/ethanol and lumin...
Figure 41: Guanidinium azacrown receptor 61 for simple amino acids and ditopic receptor 62 with crown ether an...
Figure 42: Chiral bicyclic guanidinium azacrown receptor 63 and similar receptor 64 for the enantioselective t...
Figure 43: Receptors for zwitterionic species based on luminescent CEAAs.
Figure 44: 1,10-Azacrown ethers with sugar podand arms and the anticancer agent busulfan.
Figure 45: Benzo-18-crown-6 modified β-cyclodextrin 69 and β-cyclodextrin functionalized with diaza-18-crown-6...
Figure 46: Receptors for colorimetric detection of primary and secondary ammonium ions.
Figure 47: Porphyrine-crown-receptors 72.
Figure 48: Porphyrin-crown ether conjugate 73 and fullerene-ammonium ion guest 74.
Figure 49: Calix[4]arene (75a), homooxocalix[4]arene (75b) and resorcin[4]arene (75c) compared (R = H, alkyl c...
Figure 50: Calix[4]arene and ammonium ion guest (R = H, alkyl, OAcyl etc.), possible binding sites; A: co-ordi...
Figure 51: Typical guests for studies with calixarenes and related molecules.
Figure 52: Lower rim modified p-tert-butylcalix[5]arenes 82.
Figure 53: The first example of a water soluble calixarene.
Figure 54: Sulfonated water soluble calix[n]arenes that bind ammonium ions.
Figure 55: Displacement assay for acetylcholine (3) with a sulfonato-calix[6]arene (84b).
Figure 56: Amino acid inclusion in p-sulfonatocalix[4]arene (84a).
Figure 57: Calixarene receptor family 86 with upper and lower rim functionalization.
Figure 58: Calix[6]arenes 87 with one carboxylic acid functionality.
Figure 59: Sulfonated calix[n]arenes with mono-substitution at the lower rim systematically studied on their r...
Figure 60: Cyclotetrachromotropylene host (91) and its binding to lysine (81c).
Figure 61: Calixarenes 92 and 93 with phosphonic acids groups.
Figure 62: Calix[4]arene tetraphosphonic acid (94a) and a double bridged analogue (94b).
Figure 63: Calix[4]arene tetraphosphonic acid ester (92c) for surface recognition experiments.
Figure 64: Calixarene receptors 95 with α-aminophosphonate groups.
Figure 65: A bridged homocalix[3]arene 95 and a distally bridged homocalix[4]crown 96.
Figure 66: Homocalix[3]arene ammonium ion receptor 97a and the Reichardt’s dye (97b) for colorimetric assays.
Figure 67: Chromogenic diazo-bridged calix[4]arene 98.
Figure 68: Calixarene receptor 99 by Huang et al.
Figure 69: Calixarenes 100 reported by Parisi et al.
Figure 70: Guest molecules for inclusion in calixarenes 100: DAP × 2 HCl (101a), APA (101b) and Lys-OMe × 2 HC...
Figure 71: Different N-linked peptido-calixarenes open and with glycol chain bridges.
Figure 72: (S)-1,1′-Bi-2-naphthol calixarene derivative 104 published by Kubo et al.
Figure 73: A chiral ammonium-ion receptor 105 based on the calix[4]arene skeleton.
Figure 74: R-/S-phenylalaninol functionalized calix[6]arenes 106a and 106b.
Figure 75: Capped homocalix[3]arene ammonium ion receptor 107.
Figure 76: Two C3 symmetric capped calix[6]arenes 108 and 109.
Figure 77: Phosphorous-containing rigidified calix[6]arene 110.
Figure 78: Calix[6]azacryptand 111.
Figure 79: Further substituted calix[6]azacryptands 112.
Figure 80: Resorcin[4]arene (75c) and the cavitands (113).
Figure 81: Tetrasulfonatomethylcalix[4]resorcinarene (114).
Figure 82: Resorcin[4]arenes (115a/b) and pyrogallo[4]arenes (115c, 116).
Figure 83: Displacement assay for acetylcholine (3) with tetracyanoresorcin[4]arene (117).
Figure 84: Tetramethoxy resorcinarene mono-crown-5 (118).
Figure 85: Components of a resorcinarene based displacement assay for ammonium ions.
Figure 86: Chiral basket resorcin[4]arenas 121.
Figure 87: Resorcinarenes with deeper cavitand structure (122).
Figure 88: Resorcinarene with partially open deeper cavitand structure (123).
Figure 89: Water-stabilized deep cavitands with partially structure (124, 125).
Figure 90: Charged cavitands 126 for tetralkylammonium ions.
Figure 91: Ditopic calix[4]arene receptor 127 capped with glycol chains.
Figure 92: A calix[5]arene dimer for diammonium salt recognition.
Figure 93: Calixarene parts 92c and 129 for the formation molecular capsules.
Figure 94: Encapsulation of a quaternary ammonium cation by two resorcin[4]arene molecules (NMe4+@[75c]2 × Cl−...
Figure 95: Encapsulation of a quaternary ammonium cation by six resorcin[4]arene molecules (NMe3D+@[130]6 × Cl−...
Figure 96: Structure and schematic of cucurbit[6]uril (CB[6], 131a).
Figure 97: Cyclohexanocucurbit[6]uril (CB′[6], 132) and the guest molecule spermine (133).
Figure 98: α,α,δ,δ-Tetramethylcucurbit[6]uril (134).
Figure 99: Structure of the cucurbituril-phthalhydrazide analogue 135.
Figure 100: Organic cavities for the displacement assay for amine differentiation.
Figure 101: Displacement assay methodology for diammonium- and related guests involving cucurbiturils and some ...
Figure 102: Nor-seco-Cucurbituril (±)-bis-ns-CB[6] (140) and guest molecules.
Figure 103: The cucurbit[6]uril based complexes 141 for chiral discrimination.
Figure 104: Cucurbit[7]uril (131c) and its ferrocene guests (142) opposed.
Figure 105: Cucurbit[7]uril (131c) guest inclusion and representative guests.
Figure 106: Cucurbit[7]uril (131c) binding to succinylcholine (145) and different bis-ammonium and bis-phosphon...
Figure 107: Paraquat-cucurbit[8]uril complex 149.
Figure 108: Gluconuril-based ammonium receptors 150.
Figure 109: Examples of clefts (151a), tweezers (151b, 151c, 151d) and clips (151e).
Figure 110: Kemp’s triacid (152a), on example of Rebek’s receptors (152b) and guests.
Figure 111: Amino acid receptor (154) by Rebek et al.
Figure 112: Hexagonal lattice designed hosts by Bell et al.
Figure 113: Bell’s amidinium receptor (156) and the amidinium ion (157).
Figure 114: Aromatic phosphonic acids.
Figure 115: Xylene phosphonates 159 and 160a/b for recognition of amines and amino alcohols.
Figure 116: Bisphosphonate recognition motif 161 for a colorimetric assay with alizarin complexone (163) for ca...
Figure 117: Bisphosphonate/phosphate clip 164 and bisphosphonate cleft 165.
Figure 118: N-Methylpyrazine 166a, N-methylnicotinamide iodide (166b) and NAD+ (166c).
Figure 119: Bisphosphate cavitands.
Figure 120: Bisphosphonate 167 of Schrader and Finocchiaro.
Figure 121: Tweezer 168 for noradrenaline (80b).
Figure 122: Different tripods and heparin (170).
Figure 123: Squaramide based receptors 172.
Figure 124: Cage like NH4+ receptor 173 of Kim et al.
Figure 125: Ammonium receptors 174 of Chin et al.
Figure 126: 2-Oxazolin-based ammonium receptors 175a–d and 176 by Ahn et al.
Figure 127: Racemic guest molecules 177.
Figure 128: Tripods based on a imidazole containing macrocycle (178) and the guest molecules employed in the st...
Figure 129: Ammonium ion receptor 180.
Figure 130: Tetraoxa[3.3.3.3]paracyclophanes 181 and a cyclophanic tetraester (182).
Figure 131: Peptidic bridged paraquat-cyclophane.
Figure 132: Shape-selective noradrenaline host.
Figure 133: Receptor 185 for binding of noradrenaline on surface layers from Schrader et al.
Figure 134: Tetraphosphonate receptor for binding of noradrenaline.
Figure 135: Tetraphosphonate 187 of Schrader and Finocchiaro.
Figure 136: Zinc-Porphyrin ammonium-ion receptors 188 and 189 of Mizutani et al.
Figure 137: Zinc porphyrin receptor 190.
Figure 138: Zinc porphyrin receptors 191 capable of amino acid binding.
Figure 139: Zinc-porphyrins with amino acid side chains for stereoinduction.
Figure 140: Bis-zinc-bis-porphyrin based on Tröger’s base 193.
Figure 141: BINAP-zinc-prophyrin derivative 194 and it’s guests.
Figure 142: Bisaryl-linked-zinc-porphyrin receptors.
Figure 143: Bis-zinc-porphyrin 199 for diamine recognition and guests.
Figure 144: Bis-zinc-porphyrin crown ether 201.
Figure 145: Bis-zinc-porphyrin 202 for stereodiscrimination (L = large substituent; S = small substituent).
Figure 146: Bis-zinc-porphyrin[3]rotaxane and its copper complex and guests.
Figure 147: Dien-bipyridyl ligand 206 for co-ordination of two metal atoms.
Figure 148: The ligand and corresponding tetradentate co-complex 207 serving as enantioselective receptor for a...
Figure 149: Bis(oxazoline)–copper(II) complex 208 for the recognition of amino acids in aqueous solution.
Figure 150: Zinc-salen-complexes 209 for the recognition tertiary amines.
Figure 151: Bis(oxazoline)–copper(II) 211 for the recognition of amino acids in aqueous solution.
Figure 152: Zn(II)-complex of a C2 terpyridine crown ether.
Figure 153: Displacement assay and receptor for aspartate over glutamate.
Figure 154: Chiral complex 214 for a colorimetric displacement assay for amino acids.
Figure 155: Metal complex receptor 215 with tripeptide side arms.
Figure 156: A sandwich complex 216 and its displaceable dye 217.
Figure 157: Lanthanide complexes 218–220 for amino acid recognition.
Figure 158: Nonactin (221), valinomycin (222) and vancomycin (223).
Figure 159: Monesin (224a) and a chiral analogue for enantiodiscrimination of ammonium guests (224b).
Figure 160: Chiral podands (226) compared to pentaglyme-dimethylether (225) and 18-crown-6 (4).
Figure 161: Lasalocid A (228).
Figure 162: Lasalocid derivatives (230) of Sessler et al.
Figure 163: The Coporphyrin I tetraanion (231).
Figure 164: Linear and cyclic peptides for ammonium ion recognition.
Figure 165: Cyclic and bicyclic depsipeptides for ammonium ion recognition.
Figure 166: α-Cyclodextrin (136a) and novocaine (236).
Figure 167: Helical diol receptor 237 by Reetz and Sostmann.
Figure 168: Ammonium binding spherand by Cram et al. (238a) and the cyclic[6]metaphenylacetylene 238b in compar...
Figure 169: Receptor for peptide backbone and ammonium binding (239).
Figure 170: Anion sensor principle with 3-hydroxy-2-naphthanilide of Jiang et al.
Figure 171: 7-bromo-3-hydroxy-N-(2-hydroxyphenyl)naphthalene 2-carboxamide (241) and its amine binding.
Figure 172: Naturally occurring catechins with affinity to quaternary ammonium ions.
Figure 173: Spiropyran (244) and merocyanine form (244a) of the amino acid receptors of Fuji et al.
Figure 174: Coumarin aldehyde (245) and its iminium species with amino acid bound (245a) by Glass et al.
Figure 175: Coumarin aldehyde appended with boronic acid.
Figure 176: Quinolone aldehyde dimers by Glass et al.
Figure 177: Chromogenic ammonium ion receptors with trifluoroacetophenone recognition motifs.
Figure 178: Chromogenic ammonium ion receptor with trifluoroacetophenone recognition motif bound on different m...
Enantioselective synthesis of tricyclic amino acid derivatives based on a rigid 4-azatricyclo[5.2.1.02,6]decane skeleton
- Matthias Breuning,
- Tobias Häuser,
- Christian Mehler,
- Christian Däschlein,
- Carsten Strohmann,
- Andreas Oechsner and
- Holger Braunschweig
Beilstein J. Org. Chem. 2009, 5, No. 81, doi:10.3762/bjoc.5.81
- at a more remote position of the molecule, but still in close spatial proximity to the amino function. Examples are β-proline (4) [18][19], the bispidinium salt 5 [20], and the binaphthyl-derived amino acid 6 [21][22][23], which provided excellent enantioselectivities in several aldol and Mannich
Graphical Abstract
Figure 1: The conformationally rigid amino acid derivatives 1–3 (β-turn-inducing building blocks) and 4–6 (su...
Figure 2: The targeted tricyclic amino acid derivatives 7 and 8, and the key intermediate 9.
Scheme 1: Synthesis of the racemic ketone rac-9. i) NH4OAc, HOAc, Δ, 4 d, 100%; ii) LiAlH4, THF, Δ, 1 d, 87% [24]...
Scheme 2: Enantioselective hydrosilylation/oxidation of 11. i) HSiCl3, [Pd(C3H5)Cl]2 (0.06 mol %), (R)-MOP (0...
Figure 3: X-ray crystal structure of 9. X-ray data have been deposited with the Cambridge Crystallographic Da...
Scheme 3: Initial route to the aldehyde rac-15. i) MePPh3+Br−, t-BuOK, toluene, Δ, 7 h, 77% or Mg, TiCl4, CH2...
Scheme 4: Assembly of the amino acid 7a•HCl and the N-tosylamide 7b•HCl. i) MeOCH2PPh3+Cl−, t-BuOK, toluene/T...
Scheme 5: Preparation of the amino acid 8a•HCl and the N-tosylamide 8b•HCl. i) TMSCH2CO2Et, LDA, THF, −78 °C ...
Figure 4: X-ray crystal structure of 8a•MeOH. X-ray data have been deposited with the Cambridge Crystallograp...
Can we measure catalyst efficiency in asymmetric chemical reactions? A theoretical approach
- Shaimaa El-Fayyoumy,
- Matthew H. Todd and
- Christopher J. Richards
Beilstein J. Org. Chem. 2009, 5, No. 67, doi:10.3762/bjoc.5.67
- anecdotally refer to a “good“ or “bad“ reaction, there is no system for comparing those reactions with each other. Well-known examples of asymmetric catalysis such as the Sharpless asymmetric dihydroxylation, the Corey oxazaborolidine ketone reduction or the proline-catalysed aldol reaction are almost
- asymmetric hydrogenation, which gives a product of 79% ee, is employed in the industrial multi-tonne synthesis of (S)-metolachlor [3]. An instructive comparison may be made between an antibody capable of catalysing an intramolecular, asymmetric aldol reaction and proline, capable of catalysing the same
- reaction (the Hajos–Parrish–Eder–Sauer–Wiechert reaction – entries 8 and 9). Proline performs slightly better in this reaction, despite being used at a loading of 48 mol % (!) in one of the original reports, and this is partly due to the very large molecular weight of the antibody. It can be challenging to
Graphical Abstract
Figure 1: Definition of Asymmetric Catalyst Efficiency (ACE).
A convenient method for preparing rigid-core ionic liquid crystals
- Julien Fouchet,
- Laurent Douce,
- Benoît Heinrich,
- Richard Welter and
- Alain Louati
Beilstein J. Org. Chem. 2009, 5, No. 51, doi:10.3762/bjoc.5.51
- sealed tube over 72 h to afford 1-[4-(dodecyloxy)phenyl]-1H-imidazole (A) in a good (<80%) and reproducible yield (Scheme 2). Swager has already published the synthesis of compound A under standard Ullman conditions (K2CO3, CuI, L-proline in DMSO, 16 h at 110 °C) [22]. The aryl-imidazole A was purified
Graphical Abstract
Scheme 1: 1-[4-(dodecyloxy)phenyl]-3-methyl-1H-imidazol-3-ium mesogenic salts.
Scheme 2: Synthesis of the imidazole A. Reaction conditions: (i) aryl iodide (1.37 mmol), imidazole (1.69 mmo...
Scheme 3: Synthesis of methyl imidazolium 1a. Reaction conditions: (i) MeI in sealed tube, 54 h at RT.
Figure 1: ORTEP view of compound 1a with partial labelling. The closest molecules are represented (with lower...
Figure 2: Packing diagram of compound 1a in projection in the (b,c) lattice plane. Large spheres represent th...
Scheme 4: Anion metathesis in water/CH2Cl2 as solvent.
Figure 3: Spectra of absorption (red line) and emission (blue line) of 1a.
Figure 4: TGA measurements of the compounds 1a–e (rate 10 °C·min−1, in air).
Figure 5: Phase transition temperatures of compounds 1a–e.
Figure 6: Powder X-ray diffraction pattern of compound 1a in the liquid crystal state (T = 120 °C).
Figure 7: The melting process involves the ruffling of the ionic sublayer. In the smectic phase, the ruffling...
Figure 8: Comparison of the molecular area S and of the ionic sublayer thickness dc (including mesogenic segm...
Figure 9: Variation with the counter-ion of the molecular area S and of the ionic sublayer thickness dc (incl...
Figure 10: Cyclic voltammogram of 1a in CH3CN (0.1 M NBu4PF6): (i), (ii) cathodic and anodic range of the volt...
2-Phenyl- tetrahydropyrimidine- 4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β2-amino acids
- Markus Nahrwold,
- Arvydas Stončius,
- Anna Penner,
- Beate Neumann,
- Hans-Georg Stammler and
- Norbert Sewald
Beilstein J. Org. Chem. 2009, 5, No. 43, doi:10.3762/bjoc.5.43
- employed in peptide chemistry as asparagine protective groups [52] and as proline mimetics [40]. The class of compounds described in this paper can therefore be considered as a versatile tool in peptide and amino acid chemistry. X-ray crystal structure of 10 [44]. Comparison of coupling constants (C5–C6
Graphical Abstract
Scheme 1: Selectively cleavable β2-amino acid precursors: Structures and reactivities of 2-tert-butyl-tetrahy...
Scheme 2: Cyclocondensation of Cbz-βAla-NH2 (3) and benzaldehyde. a) [p-TsOH], toluene, reflux, Dean–Stark tr...
Scheme 3: Protection and deprotection of 4. a) Boc2O, DMAP, CH3CN, 16 h, rt; b) 1. n-BuLi, THF, −78 °C, 30 mi...
Scheme 4: Synthesis of enantiopure 2-phenyl-tetrahydropyrimidine-4(1H)-ones. a) PhCH(OMe)2, BF3·Et2O (6.0 equ...
Figure 1: X-ray crystal structure of 10 [44].
Scheme 5: Diastereoselective alkylation of 5.
Figure 2: Comparison of coupling constants (C5–C6-ABX system) within the 1H-NMR spectra of literature known c...
Figure 3: Supposed enolate conformations.
Scheme 6: Selective ring opening of the heterocycle 11d and isolation of orthogonally protected β2-homoaspart...
Asymmetric synthesis of biaryl atropisomers by dynamic resolution on condensation of biaryl aldehydes with (−)-ephedrine or a proline- derived diamine
- Ann Bracegirdle,
- Jonathan Clayden and
- Lai Wah Lai
Beilstein J. Org. Chem. 2008, 4, No. 47, doi:10.3762/bjoc.4.47
- Ann Bracegirdle Jonathan Clayden Lai Wah Lai School of Chemistry, University of Manchester, Oxford Rd., Manchester M13 9PL, UK 10.3762/bjoc.4.47 Abstract Atropisomeric biaryl aldehydes undergo diastereoselective condensation with (−)-ephedrine and with a proline-derived diamine, with selectivity
- ] and ureas [18][19][20], we have explored the opportunities offered by dynamic kinetic [21][22][23] and dynamic thermodynamic [24] resolution [11][16][25][26][27][28][29][30]. We reported methods for the latter based on resolving “auxiliaries” which include silylethyl groups [28], proline-derived
- substrates Previous success with stereocontrol employing ephedrine-derived oxazolidines [15][26][27][34][35] and proline-derived imidazolidines [25][27] prompted us to investigate the thermal stability and conformational preferences of similar products arising from condensation reactions of 2-formylbiaryls
Graphical Abstract
Scheme 1: Synthesis of racemic aldehydes.
Scheme 2: Diastereoisomeric imidazolidines and oxazolidines from biaryl aldehydes.
Figure 1: X-ray crystal structure of 9a. X-ray data has been deposited with the Cambridge Crystallographic Da...
Figure 2: X-ray crystal structure of 10a. X-ray data has been deposited with the Cambridge Crystallographic D...
Scheme 3: Atropisomeric alcohols by hydrolysis and reduction.
Scheme 4: Mechanistic rationalisation of the dynamic resolution in the formation of 9.
Synthesis of (S)-1-(2-chloroacetyl)pyrrolidine- 2-carbonitrile: A key intermediate for dipeptidyl peptidase IV inhibitors
- Santosh K. Singh,
- Narendra Manne and
- Manojit Pal
Beilstein J. Org. Chem. 2008, 4, No. 20, doi:10.3762/bjoc.4.20
- -carbonitrile was achieved. Reaction of L-proline with chloroacetyl chloride was followed by conversion of the carboxylic acid moiety of the resulting N-acylated product into the carbonitrile via the corresponding amide intermediate. The synthesized pyrrolidine derivative was utilized to prepare DPP-IV
- inhibitor Vildagliptin. Keywords: amides; DPP-IV inhibitors; L-proline; N-acylation; 2(S)-cyanopyrrolidine; Background One of the emerging and mechanism based approaches for the treatment of type-II diabetes is dipeptidyl peptidase IV (DPP-IV; CD26; E.C. 3.4.14.5) inhibition with the help of small
- molecules [1][2][3]. DPP-IV, a member of the prolyl oligopeptidase family of serine protease, cleaves the N-terminal dipeptide from peptides with proline or alanine in the second position. As a result of intense pharmaceutical research, several DPP-IV inhibitors have been discovered and a few of them
Graphical Abstract
Figure 1: DPP-IV Inhibitors.
Figure 2: Role of 2(S)-cyanopyrrolidine moiety in DPP-IV inhibition.
Scheme 1: Earlier route to (S)-1-(2-chloroacetyl)pyrrolidine-2-carbonitrile (6).
Scheme 2: Synthesis of (S)-1-(2-chloroacetyl)pyrrolidine-2-carbonitrile (6).
Scheme 3: Preparation of Vildagliptin (2).
