Facile synthesis of a 3-deazaadenosine phosphoramidite for RNA solid-phase synthesis

• Elisabeth Mairhofer,
• Elisabeth Fuchs and
• Ronald Micura

Beilstein J. Org. Chem. 2016, 12, 2556–2562, doi:10.3762/bjoc.12.250

• to use 6-azido-3-deazapurine ribonucleoside as key intermediate Our initial attempts to create an efficient route to c3A started with the smooth transformation of commercially available 4-chloroimidazo[4,5-c]pyridine with lithium azide to provide 4-azidoimidazo[4,5-c]pyridine (1) [27] (Scheme 3

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

• Nikolay O. Chalkov,
• Vladimir K. Cherkasov,
• Gleb A. Abakumov,
• Andrey G. Starikov and
• Viacheslav A. Kuropatov

Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238

• of the quinone 2. Hyperfine splitting constants and g-factors of protonated semiquinones. The values in brackets correspond to the analogous lithium derivatives. Supporting Information Supporting Information File 320: Additional material. Acknowledgements We gratefully acknowledge the financial

A new paradigm for designing ring construction strategies for green organic synthesis: implications for the discovery of multicomponent reactions to build molecules containing a single ring

• John Andraos

Beilstein J. Org. Chem. 2016, 12, 2420–2442, doi:10.3762/bjoc.12.236

• a cyclic enamine followed by reductive elimination of the amine moiety using lithium in liquid ammonia [150]. We may be able to repeat the exercise now using all possible 3-partition target bond dissection maps shown in Figure 6. For brevity the results are given in Supporting Information File 1 in

β-Amino functionalization of cinnamic Weinreb amides in ionic liquid

• Yi-Ning Wang,
• Guo-Xiang Sun and
• Gang Qi

Beilstein J. Org. Chem. 2016, 12, 2372–2377, doi:10.3762/bjoc.12.231

• amides [21][22][23][24][25][26]. Another approach was the direct amination of α,β-unsaturated Weinreb amides by using lithium (S)-N-benzyl-N-α-methylbenzylamide as the nitrogen source [27][28][29]. Recently, a new chiral N-phosphonylimine chemistry was developed by the Li group. By reacting N

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• : Our modified synthesis of BTR and its analogues starts with the lithiation of 3-alkylthiophene 1a–c by lithium diisopropylamide formed in situ from the reaction of n-butyllithium with diisopropylamine (DIA) in the presence of the alkylthiophene, followed by quenching with trimethylsilyl chloride to

Isosorbide and dimethyl carbonate: a green match

• Fabio Aricò and
• Pietro Tundo

Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218

• . Recently DCI has been also prepared via DMC chemistry in the presence of lithium acetylacetonate (Li(acac)) as catalyst [85]. Dicarboxymethyl isosorbide, once formed, has been directly converted into either homo- or co-polycarbonate via an easy straight-forward procedure (Scheme 4). In the case of

Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties

• Pierre Boufflet,
• Sebastian Wood,
• Jessica Wade,
• Zhuping Fei,
• Ji-Seon Kim and
• Martin Heeney

Beilstein J. Org. Chem. 2016, 12, 2150–2163, doi:10.3762/bjoc.12.205

• at every 10 °C interval in order to measure spectra. Typical procedure for the synthesis of Grignard monomer To a solution of 2,5-dibromo-3-octylthiophene (361.2 mg, 1.02 mmol) in dry THF (2.86 mL) at room temperature was added isopropylmagnesium chloride lithium chloride complex (0.78 mL, 1.3 M in

Synthesis of medronic acid monoesters and their purification by high-performance countercurrent chromatography or by hydroxyapatite

• Elina Puljula,
• Jouko Vepsäläinen and
• Petri A. Turhanen

Beilstein J. Org. Chem. 2016, 12, 2145–2149, doi:10.3762/bjoc.12.204

• , Michaelis–Arbuzov and carbanion methods. From these three the carbanion method has been proposed to be the most convenient approach to produce mixed tetraesters, but it requires extremely dry conditions because of the use of lithium diisopropylamide (LDA) [27]. Methylenebis(phosphonic dichloride) [29][32

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

• Dominik Urselmann,
• Konstantin Deilhof,
• Bernhard Mayer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194

• our one-pot bromine-lithium-exchange-borylation-Suzuki (BLEBS) sequence [78], employing an excess of 3,7-dibromo-10-hexyl-10H-phenothiazine (3) [45] as a coupling component in the Suzuki step (Scheme 1). With three bromo-substituted (oligo)phenothiazines 1 in hand the consecutive pseudo five-component

• oligophenothiazines 3 (calculated with the B3LYP functional in vacuo and the 6-311G(d,p) basis set). One-pot bromine-lithium-exchange-borylation-Suzuki (BLEBS) synthesis of 7-bromo-substituted phenothiazines 1b and 1c with 3,7-dibromo-10-hexyl-10H-phenothiazine (2). Pseudo five-component Sonogashira-Glaser

Synthesis of pyrrolo[2,1-f][1,2,4]triazin-4(3H)-ones: Rearrangement of pyrrolo[1,2-d][1,3,4]oxadiazines and regioselective intramolecular cyclization of 1,2-biscarbamoyl-substituted 1H-pyrroles

• Kkonnip Son and
• Seong Jun Park

Beilstein J. Org. Chem. 2016, 12, 1780–1787, doi:10.3762/bjoc.12.168

• 1, Table 2). In the cases of Li[Me3AlSPh], NaSMe, and NaOMe, the triazinone 12a was readily obtained after the nucleophilic-addition/ring-closure reaction (entries 2–5, Table 2). For example, similar to benzoxazine [22], treatment of 11a and 11d with lithium trimethyl(phenylsulfido)aluminate Li

• to 12a, the mechanism of the nucleophile-induced cyclization is proposed after considering Hart’s research on the synthesis of fumiquinazolines [22]. It was shown that the nucleophilicity of the N-acylnitrenium ion was increased when the oxygen ion was stabilized by counter ions such as lithium and

• conditions (0 °C, 5 min). The regioselectivity was influenced by the identities of halogen sources of triphenylphosphorane and the N-functional groups. For the rearrangement reaction, it was demonstrated that triazinone 12a was easily obtained when counter ions of oxygen such as lithium and sodium were used

Automated glycan assembly of a S. pneumoniae serotype 3 CPS antigen

• Markus W. Weishaupt,
• Stefan Matthies,
• Mattan Hurevich,
• Claney L. Pereira,
• Heung Sik Hahm and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2016, 12, 1440–1446, doi:10.3762/bjoc.12.139

• using a mixture of lithium hydroxide and hydrogen peroxide to avoid elimination reactions which are common for uronic acid methyl esters under strongly basic conditions [30][32]. In the next step, the remaining esters were removed employing sodium hydroxide in methanol. Finally, catalytic hydrogenation

From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

• Daniela Obels,
• Melanie Lievenbrück and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133

• physiological compatibility [1][2][3][4][5][6][7]. It is used as additive, e.g., in cosmetics [8], pharmaceutical preparations [9][10][11][12] and food industry (additive E 1201) [13]. Monoalkylation reactions of N-VP in α-position via deprotonation by lithium diisopropylamide [14] were carried out to open up

• ) can be mono or di-deprotonated in α-position to the carbonyl group by the use of the strong and sterically demanding base lithium diisopropylamide [14][34][35]. As mentioned above, the resulting carbanions do not attack the electron-rich N-vinyl double bond. Accordingly, by using 1,8-dibromooctane as

Selective bromochlorination of a homoallylic alcohol for the total synthesis of (−)-anverene

• Frederick J. Seidl and
• Noah Z. Burns

Beilstein J. Org. Chem. 2016, 12, 1361–1365, doi:10.3762/bjoc.12.129

• stoichiometric generation of the lithium carbanion of 9 with n-BuLi prior to addition of the corresponding aldehyde, and by maintaining very short (<10 minutes) reaction times at 0 °C. This protocol led to complete conversion exclusively to the E-unsaturated ester without any observed elimination. The

Reactivity studies of pincer bis-protic N-heterocyclic carbene complexes of platinum and palladium under basic conditions

• David C. Marelius,
• Curtis E. Moore,
• Arnold L. Rheingold and
• Douglas B. Grotjahn

Beilstein J. Org. Chem. 2016, 12, 1334–1339, doi:10.3762/bjoc.12.126

• .12.126 Abstract Bis-protic N-heterocyclic carbene complexes of platinum and palladium (4) yield dimeric structures 6 when treated with sodium tert-butoxide in CH2Cl2. The use of a more polar solvent (THF) and a strong base (LiN(iPr)2) gave the lithium chloride adducts monobasic complex 7 or analogous

• , Figure 2), a situation that would not be possible for a monomeric structure. Attempts to synthesize 5 using sodium alkoxide bases led to the formation of dimer structures 6 with presumed loss of NaCl. Therefore, lithium chloride adducts 7 were targeted because LiCl adduct 3 was isolable yet highly

• insight (Table 2), as exemplified by 1–3 [10]. The Δx (difference in 15N shifts for compound x) is near zero for a PNHC (1), maximum for the imidazolyl conjugate base 2, and slightly less for an imidazolyl lithium chloride adduct 3. The δN for the aprotic nitrogen incapable of acid base chemistry (N2

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• dephosphorylated by treatment with lithium aluminum hydride to give isoindolin-1-ones 61 (Scheme 15). Also the Kabachnik–Fields reaction of formylbenzoic acid (55), dimethyl phosphonate and amines 62 or 66 followed by subsequent Horner–Wadsworth–Emmons reaction of the resulting cycloadducts 63 and 67 with

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

• Jakub Saadi,
• Christoph Bentz,
• Kai Redies,
• Dieter Lentz,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1236–1242, doi:10.3762/bjoc.12.118

• of organometallics such as lithium, magnesium or zinc organic compounds to carbonyl groups leading to alcohols is an important standard operation in organic synthesis providing high stereoselectivities in many cases. The in situ generation of the nucleophilic species from the corresponding organic

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• . Also, esters are not as electron deficient as many other electron withdrawing groups, and therefore, the presence of additional activating groups on the alkene or the use of a highly activating catalyst are often required. In 2001, Tomioka and co-workers reported the addition of lithium arylthiolates

• , catalytically generated from 1, to α-substituted acrylates 2 followed by enantioselective protonation of the resulting lithium enolate (Scheme 1) [14]. The ortho-trimethylsilyl substituent on the phenyl ring was necessary for achieving high levels of enantioselectivity. All of the reactions proceeded in high

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• lithium aluminum hydride in excellent yield. The absolute configuration of the [3.1.0] pyrrolidines was assigned by analogy to 76, which was determined to be (R,R) by single crystal X-ray crystallography. Mechanistic studies After having successfully developed this synthetic methodology, a few questions

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• effects on the enantioselectivity. Compared to acetone and cycloheptanone, good enantioselectivities were obtained for cyclohexanone. Based on the previously observed catalytic performance of amino acid metal salts in asymmetric catalysis, Luo and co-workers reported that phenylalanine lithium salt (cat

• . 8) can efficiently catalyze the aldol reaction of substituted isatins with ketones, allowing facile access to the 3-hydroxyoxindoles in moderate to good yields (73–97% yield) and with good enantioselectivity (66–90% ee, Scheme 21) [37]. The phenylalanine lithium salt was easily prepared from

A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

• Vladislav Vasilenko,
• Torsten Roth,
• Clemens K. Blasius,
• Sebastian N. Intorp,
• Hubert Wadepohl and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 846–853, doi:10.3762/bjoc.12.83

• throughout the reaction, the resulting mixtures do not require a purification step beyond a filtration from toluene or hexane to remove residual lithium chloride. As has been pointed out by Dyer et al. for the structurally related N-phosphanylamidines, there are several distinct conformers of ligands 2a–c

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

• M. Emin Cinar,
• Bernward Engelen,
• Martin Panthöfer,
• Hans-Jörg Deiseroth,
• Jens Schlirf and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 813–824, doi:10.3762/bjoc.12.80

• benzaldehyde (3a: Ar = Ph) (Scheme 2). The enolate was generated from propiophenone by deprotonation with lithium diisopropylamide (LDA) at −40 °C in tetrahydrofuran (THF) and was subsequently reacted with 0.33 equivalents of MCl3 or 0.25 equivalents of MCl4, respectively. The resulting metal enolate was then

Synthesis and in vitro cytotoxicity of acetylated 3-fluoro, 4-fluoro and 3,4-difluoro analogs of D-glucosamine and D-galactosamine

• Štěpán Horník,
• Lucie Červenková Šťastná,
• Petra Cuřínová,
• Jan Sýkora,
• Kateřina Káňová,
• Roman Hrstka,
• Ivana Císařová,
• Martin Dračínský and
• Jindřich Karban

Beilstein J. Org. Chem. 2016, 12, 750–759, doi:10.3762/bjoc.12.75

• :3,4-dianhydro derivative 17. Formation of the triflate ester and azidolysis furnished 1,6:3,4-dianhydro-2-azido derivative 18. Lithium azide was found superior to sodium azide in conversion of the triflate to the azide 18, and the yield of 18 increased from 48% reported earlier [46] to 82%. The

• ]. Azidolysis of the oxirane ring in the reaction with lithium azide furnished 2-azido derivative 31. Although nucleophilic cleavage of a three-membered ring annulated to the 1,6-anhydrohexopyranose skeleton usually occurs solely in trans-diaxial fashion [50], formation of the trans-diequatorial side-product 32

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• . However, by control of stoichiometry and the nature of the organo-lithium only a grand total of ten different products of the possible sixty-nine can be formed. Hence by careful control of the conditions, compounds ranging from the mono-endo substituted to tetra-exo-substituted (Scheme 7) can be isolated

My maize and blue brick road to physical organic chemistry in materials

• Anne J. McNeil

Beilstein J. Org. Chem. 2016, 12, 229–238, doi:10.3762/bjoc.12.24

• on a project aimed at understanding why a lithium enolate alkylation stalled at 70% conversion during a key step in the preparative scale synthesis of a factor Xa inhibitor at Aventis. At the time, identifying solution structures of lithium enolates by NMR spectroscopy was challenging owing to the

• emerged was a beautiful story [3][4][5] (and method) that is still being used to determine the aggregation state of lithium enolates [6][7][8][9] and alkoxides [10][11][12][13]. From Dave, I learned a tremendous amount about being a scientist. One of the most important take-home messages was that all data

Catalytic asymmetric formal synthesis of beraprost

• Yusuke Kobayashi,
• Ryuta Kuramoto and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2015, 11, 2654–2660, doi:10.3762/bjoc.11.285

• yield (Table 1, entry 8). With both the AIOM adducts 5 and 6 in hand, we next investigated the construction of the tricyclic core (Scheme 3 and Scheme 4). The cross-Claisen condensation of 6 with lithium tert-butyl acetate afforded the corresponding β-ketoester, which was then treated with 2-azido-1,3

• benzylic bromination followed by elongation of the C3 unit [22]. To this end, the ester group at the C1 position of 15 was reduced by lithium borohydride, and the resultant 1,3-diol protected to give acetal 16 [16]. After various experiments, selective bromination of the methyl group on the aromatic ring

• % yield (dr > 10:1) via the method established in Scheme 3. After derivatization to acetal 22 in 2 steps, we then turned our attention to the introduction of the C4 ester substituents. Amongst various different conditions investigated – including Pd-catalyzed coupling reactions – a halogen-lithium