Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• ) derivatives and dipeptides. In this regard, trimerization and Negishi cross-coupling reactions are used as the key steps starting from readily available 4’-iodoacetophenone and L-serine. These C3-symmetric molecules containing AAA moieties are useful to design new ligands suitable for asymmetric synthesis and

• . Results and Discussion The required zinc insertion compound 7 was prepared from L-serine (3). Thus, commercially available L-serine (3) was treated with acetyl chloride in methanol to give methyl ester 4, which was subjected to N-Boc protection with di-tert-butyl dicarbonate (Boc2O) and triethylamine in

• containing unusual AAA units through cyclotrimerization and Negishi cross-coupling reaction as key steps under operationally simple reaction conditions. Here, we have used the readily available starting materials 4-iodoacetophenone (8) and L-serine (3). The C3-symmetric building blocks prepared were coupled

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• )-2 and (2S,3S)-2 in several steps including hydroxymethyl to carboxyl oxidations (Scheme 2) [50]. N-Fmoc protection of the amino group in L-serine together with transformation of the carboxylic function into an orthoester allow for the racemization-free oxidation to aldehyde 10, which was immediately

• -protected acid 13 derived from L-serine with allylmagnesium bromide provided ketone 14 which was reduced to diastereoisomeric diols in a 9:1 syn to anti ratio when L-selectride was applied. They were separated as isopropylidene derivatives and the syn isomer 15 was subjected to ozonolysis and oxidation to

• aldehyde (S)-18 prepared from O-benzyl-L-serine in three standard steps [53] was elongated by a two-carbon fragment employing a Wittig reaction to give Z-alkene 19. To introduce the next center of chirality of the required configuration a iodocyclocarbamation reaction was applied to give trans-oxazolidin-2

Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• such intermediates. By selecting the appropriate reaction conditions (various pH and temperatures), they were able to alkylate free amino acids, e.g., glycine (Gly), L-serine (Ser), L-cysteine (Cys), L-lysine (Lys), L-tyrosine (Tyr) and glutathione (Glu) in aqueous solution to isolate 55 (Scheme 8

The use of 4,4,4-trifluorothreonine to stabilize extended peptide structures and mimic β-strands

• Yaochun Xu,
• Isabelle Correia,
• Tap Ha-Duong,
• Nadjib Kihal,
• Jean-Louis Soulier,
• Julia Kaffy,
• Benoît Crousse,
• Olivier Lequin and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2017, 13, 2842–2853, doi:10.3762/bjoc.13.276

• Sorbonne Universités, UPMC Univ Paris 06, Ecole Normale Supérieure, PSL Research University, CNRS, Laboratoire des Biomolécules, 4 place Jussieu, 75252 Paris Cedex 05, France 10.3762/bjoc.13.276 Abstract Pentapeptides having the sequence R-HN-Ala-Val-X-Val-Leu-OMe, where the central residue X is L-serine

• proteins aggregation characterized by ordered β-sheet structure assemblies [14][15]. In this context, we synthesized and analyzed, by NMR and molecular modeling, the conformational preferences of eight pentapeptides, containing a L-serine, a L-threonine, a (2S,3R)-L-allo-CF3-threonine or a (2S,3S)-L-CF3

• that the presence of fluorine atoms probably increased the interaction of pentapeptides with Aβ1-42 and their inhibitory effect on Aβ1-42 aggregation. Conclusion We synthesized eight pentapeptides 1a–4a and 1b–4b having the sequence RHN-Ala-Val-X-Val-Leu-OMe, where the central residue X is L-serine, L

Remarkable functions of sn-3 hydroxy and phosphocholine groups in 1,2-diacyl-sn-glycerolipids to induce clockwise (+)-helicity around the 1,2-diacyl moiety: Evidence from conformation analysis by ¹H NMR spectroscopy

• Yoshihiro Nishida,
• Mengfei Yuan,
• Kazuo Fukuda,
• Kaito Fujisawa,
• Hirofumi Dohi and
• Hirotaka Uzawa

Beilstein J. Org. Chem. 2017, 13, 1999–2009, doi:10.3762/bjoc.13.196

• = 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, DPPS = 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine, DPPA = 1,2-dipalmitoyl-sn-glycerol 3-phosphate. Chirally 2H-labelled tripalmitins (1S)- and (1R)-1-[2H]-1 [23]. 1H NMR data and helical conformational properties of tripalmitin 1 and 3-O-benzyl

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• extension. Based on the presumed biosynthetic origin of these extender units (from L-serine and from a glycolytic intermediate (in all likelihood 1,3-biphospho-D-glycerate), respectively), it was initially proposed that the (2S)-isomer of aminomalonyl-ACP and the (2R)-isomers of hydroxyl-/methoxymalonyl-ACP

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• containing substrates such as the p-nitrophenyl carbonate of 9-fluorenemethanol 16a and N-Cbz-L-serine methyl ester 17a, resulted in the dibenzofulvene product 16b in the former, and a mixture of products in the latter, with DBN acting as a base. Even though the γ-lactam products were the only major

TMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals

• Mei-Yuan Hsu,
• Yi-Pei Liu,
• Sarah Lam,
• Su-Ching Lin and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2016, 12, 1758–1764, doi:10.3762/bjoc.12.164

• -butanol (16), 5-azidopentanol (17), cyclohexanol (18) and 2-adamantanol (19), to give O-2-deoxyglucosides in high yields (74–90%) and α-selectivities (α:β = 7–10:1, Table 3, entries 2–8). Regarding the glycosylation with amino acid derivatives, L-serine 20 and threonine derivative 21, increased ratio of β

• ). Glycosylation with MeOH (13); however, produced 52 in an excellent yield but lower selectivity (95%, α:β = 4:1, Table 4, entry 2). The bulky acceptor 2-adamantanol (19) produced compound 58 in a decreased yield but with excellent selectivity because of its low solubility (43%, α:β = 13:1, Table 4, entry 8). L

• -Serine and threonine derivatives 20 and 21 reacted with galactal 4 to give the glycosylated amino acids 59 and 60 (Table 4, entries 9 and 10) in excellent selectivities (59, α only; 60, α:β = 9:1) but in different yields (59, 50%; 60, 97%). In Table 4, entry 11, disaccharide 61 was acquired in the

One-pot synthesis of enantiomerically pure N-protected allylic amines from N-protected α-amino esters

• Gastón Silveira-Dorta,
• Sergio J. Álvarez-Méndez,
• Víctor S. Martín and
• José M. Padrón

Beilstein J. Org. Chem. 2016, 12, 957–962, doi:10.3762/bjoc.12.94

• also with free hydroxy groups present in the substrate, as it has been shown earlier for a N-Boc protected amino hydroxy ester [21]. To corroborate this idea, N,N-dibenzylamino benzyl ester of L-serine (3) was submitted to the one-pot tandem reduction–olefination procedure described above

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• of L-serine dissolved in glacial acetic acid saturated with HCl. After storage for 15 h, the solvent was evaporated under reduced pressure and the process was repeated (Scheme 3) [16]. The rather forcing conditions are probably a result of not employing a more reactive acylating agent than acetic

• yield. Their procedure was also adopted by others, as reported by Fasman and Blout in 1960 for the O-acetylation of L-serine and DL-serine [17], by Arakawa, Smeby and Bumpus for L-serine in 1962 [18] and by Fujiwara, Morinaga and Narita in 1962 for L-serine, DL-threonine and D-threonine [19]. Although

• -L-proline, L-serine, DL-serine and L-threonine were all obtained directly in excellent purity in over 90% yield at >10 g scale. Early O-acylation of hydroxyamino acids in trifluoroacetic acid As narrated in the previous section, developments taking place from the early 1940s into the early 1960s had

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• deleterious epimerization of the existing stereocenter in Garner’s aldehyde. Keywords: asymmetric synthesis; Garner’s aldehyde; natural product synthesis; L-serine; Introduction “The universe is a dissymmetrical whole. I am inclined to think that life, as manifested to us, must be a function of the

• reduction can be used. The ester can be reduced to alcohol 6 (e.g., with NaBH4/LiCl) and then oxidized to 1 with non-basic methods (e.g., IBX/DMP [30] or TEMPO/NaOCl [31] to name a few), which will not epimerize the α-center. For our synthesis of 1, we adopted a slightly modified sequence [32]. L-Serine (2

• the reaction temperature below −75 °C. This allowed us to isolate the aldehyde (S)-1 in 97% ee. This reaction sequence was performed in more than 1.0 mol scale starting from L-serine and the reduction to Garner’s aldehyde was performed on a 0.5 mol scale. DIBAL-H is an efficient reducing agent, but at

Stereodivergent synthesis of jaspine B and its isomers using a carbohydrate-derived alkoxyallene as C₃-building block

• Volker M. Schmiedel,
• Stefano Stefani and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2013, 9, 2564–2569, doi:10.3762/bjoc.9.291

• than 30 published syntheses up to now. Most frequently they are based on transformations of starting materials available from the ”chiral pool”, e.g. L-serine [7][8][9][10][11][12][13][14][15][16][17][18], or by asymmetric catalysis [19][20][21][22][23][24][25]. Several publications also focused on the

Isotopically labeled sulfur compounds and synthetic selenium and tellurium analogues to study sulfur metabolism in marine bacteria

• Nelson L. Brock,
• Christian A. Citron,
• Claudia Zell,
• Martine Berger,
• Irene Wagner-Döbler,
• Jörn Petersen,
• Thorsten Brinkhoff,
• Meinhard Simon and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 942–950, doi:10.3762/bjoc.9.108

• second obvious candidate as a source for sulfur volatiles is inorganic sulfate, which can be reduced by Roseobacter clade members to hydrogen sulfide via adenylyl sulfate, 3’-phosphoadenylyl sulfate, and sulfite (Scheme 2) [17]. Hydrogen sulfide enters the amino acid pool by reaction with O-acetyl-L

• -serine to L-cysteine. Elemental sulfur, hydrogen sulfide, or thiosulfate can be funneled via the lithotrophic sulfur oxidation (Sox) pathway to sulfate [18][19][20][21][22]. Analogous degradation steps for the selenium and tellurium derivatives of DMSP (dimethylseleniopropionate, DMSeP, and

Palladium-catalyzed C–N and C–O bond formation of N-substituted 4-bromo-7-azaindoles with amides, amines, amino acid esters and phenols

• Rajendra Surasani,
• Dipak Kalita,
• A. V. Dhanunjaya Rao and
• K. B. Chandrasekhar

Beilstein J. Org. Chem. 2012, 8, 2004–2018, doi:10.3762/bjoc.8.227

• short reaction time (Table 6, entry 2). The chiral purity of the product was determined by chiral HPLC using Chiral Pak AD-H column. Amino acids without extra coordinating groups gave good coupling yields (Table 6, entries 3, 6 and 7). Coupling of L-serine(O-t-Bu)-OMe (6d) with 1c resulted in moderate

• yield of the product in 3 h (Table 6, entry 4). The catalytic system developed by us for the coupling of amino acid esters with N-protected 7-azaindoles was ineffective for L-proline (6f), L-serine (6g), and L-glutamic acid (6h) (Table 6, entries 8–10). This may be ascribed to the fact that these amino

Coupled chemo(enzymatic) reactions in continuous flow

• Ruslan Yuryev,
• Simon Strompen and
• Andreas Liese

Beilstein J. Org. Chem. 2011, 7, 1449–1467, doi:10.3762/bjoc.7.169

• D-xylulose (28) from D,L-serine (26) and D,L-glyceraldehyde (25) involving three enzymes in a single continuously stirred tank reactor (CSTR) was presented by Bongs (Scheme 9) [32]. Here, a D-amino acid oxidase was used to form hydroxypyruvic acid (27) from D-26, which was subsequently converted to

• resolution of (rac)-1-phenylethanol (22) in supercritical CO2 in a packed-bed reactor loaded with acidic zeolite (A) and Novozym 435 (E) [30]. Synthesis of D-xylulose (28) from D,L-serine (26) and D,L-glyceraldehyde (25) in a continuously operated enzyme membrane reactor. E1: D-Amino acid oxidase; E2

Metathesis access to monocyclic iminocyclitol-based therapeutic agents

• Ileana Dragutan,
• Valerian Dragutan,
• Carmen Mitan,
• Hermanus C.M. Vosloo,
• Lionel Delaude and
• Albert Demonceau

Beilstein J. Org. Chem. 2011, 7, 699–716, doi:10.3762/bjoc.7.81

• affords the pentahydroxy derivative 149. Starting from L-serine 150, Lin et al. [81] devised a refined method for the synthesis of structurally diverse stereoisomers of polyhydroxyazepanes. In their complex strategy, RCM (1st-generation Grubbs catalyst, 10 mol %, CH2Cl2, reflux, 12 h) plays a significant

An enantiomerically pure siderophore type ligand for the diastereoselective 1 : 1 complexation of lanthanide(III) ions

• Markus Albrecht,
• Olga Osetska,
• Thomas Abel,
• Gebhard Haberhauer and
• Eva Ziegler

Beilstein J. Org. Chem. 2009, 5, No. 78, doi:10.3762/bjoc.5.78

• chelating moiety, which can form highly stable complexes with a series of first row transition metals. (ii) Chirality: The enterobactin-backbone is based on L-serine units and therefore is chiral (and enantiomerically pure). This chiral information gives all three ligand units the same spatial orientation