Advancements in hydrochlorination of alkenes

• Daniel S. Müller

Beilstein J. Org. Chem. 2024, 20, 787–814, doi:10.3762/bjoc.20.72

• more efficient reactions with alkene 88 (Table 6). In 2022, Oestreich reported the in situ formation of HCl by Lewis acid-induced Grob fragmentation of acid chloride 92 (Scheme 15B) [68]. The inconvenience of this method is that 92 has to be prepared in two steps, including a Birch reduction (Scheme

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• allowed the delivery of trans-decalin 85 in a gram-scale quantity. Birch reduction of the electron-rich aromatic ring, followed by propargylic addition and functional group interconversion (FGI) provided dienyne 86. Compound 86, under the previously developed radical reductive cyclization for 1,6-dienyne

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• synthesis, the authors followed the strategy developed previously by Marinovi’s group to form the bicyclo[3.2.1]octane moiety [39]. The synthesis started from 64 with a one-pot Birch reduction/alkylation with vinyl bromide 65, affording 66 in 68% yield over two steps. Next the construction of the bicylo

Total synthesis of ent-pavettamine

• Memory Zimuwandeyi,
• Manuel A. Fernandes,
• Amanda L. Rousseau and
• Moira L. Bode

Beilstein J. Org. Chem. 2021, 17, 1440–1446, doi:10.3762/bjoc.17.99

• yield of 84%. The Boc group was chosen for the re-protection of the amine, furnishing 21 in quantitative yield. Due to the significant difference between the trityl and the Boc groups, selective trityl removal was now possible under Birch reduction conditions. The primary alcohol 22 was recovered in an

Synthesis of acremines A, B and F and studies on the bisacremines

• Nils Winter and
• Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

• traced back to silyl enol ether 10. Ent-10 was first reported by Herzon and co-workers [9] and is derived from phenol silyl ether 11 via Birch reduction and dihydroxylation. Results and Discussion Our synthesis started with meta-cresol (12) which was protected as a TIPS ether and then subjected to Birch

• reduction conditions to afford cyclohexa-1,4-diene 13 [9]. Enantioselective Sharpless dihydroxylation proceeded in good chemoselectivity but with modest yield and optical purity (25% ee). Unfortunately, all attempts to improve the enantioselectivity of this reaction failed. We discovered, however, that at a

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• -(iodomethyl)oxazolidin-2-one (4R,1'S)-39 via a regioselective opening with iodide and cyclization (Scheme 12) [50]. As expected alkylation of the indole ring with (4R,1'S)-39 occurred at C3 to give (4S,1'S)-40 which was deprotected in two steps (Birch reduction and alkaline hydrolysis) to provide ʟ

• hydrolysis. Installation of the allyl group at the nitrogen atom required prior derivatization as an oxazolidin-2-one and Birch reduction to furnish 204. To construct a properly functionalized piperidine ring olefin metathesis was performed to supply the key intermediate 205. Taking advantage of the steric

Synthetic and semi-synthetic approaches to unprotected N-glycan oxazolines

• Antony J. Fairbanks

Beilstein J. Org. Chem. 2018, 14, 416–429, doi:10.3762/bjoc.14.30

• protecting groups revealed the 6-hydroxy groups of the terminal mannose residues, which were then phosphorylated. Removal of the anomeric PMP protection was followed by global deprotection by Birch reduction to give the completely deprotected tetrasaccharide diphosphate. Finally treatment with DMC in water

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• , multi-step intermediates and the final debenzylation is achieved by using the highly inconvenient Birch reduction. 4 Direct activation of the anomeric center Over the past 20 years, primarily the Shoda, Fairbanks, and Nitz groups have performed extensive studies on molecules that selectively react at

Fluorinated cyclohexanes: Synthesis of amine building blocks of the all-cis 2,3,5,6-tetrafluorocyclohexylamine motif

• Tetiana Bykova,
• Nawaf Al-Maharik,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2017, 13, 728–733, doi:10.3762/bjoc.13.72

• building blocks for discovery chemistry programmes. The synthesis starts from a Birch reduction of benzonitrile, followed by an in situ methyl iodide quench. The resultant 2,5-cyclohexadiene was progressed via double epoxidations and then hydrofluorination ring opening reactions. The resultant fluorohydrin

• -tetrafluorocyclohexane aldehydes 4 were used successfully in Ugi multicomponent reactions [11][12]. In this paper we report the preparation of amines of this series starting from a Birch reduction on benzonitrile, and with a similar methyl iodide quench, to generate amines 5, which are stable to hydrogen fluoride

• elimination. Results and Discussion The Birch reduction of benzonitrile 6 followed by in situ methylation with iodomethane generated cyclohexadiene 7 as previously described [13][14]. Cyclohexadiene 7 was then subjected to a double epoxidation protocol using mCPBA [1][11][15][16]. This generated three

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• conditions allow the reduction of various other functional groups [28]. Rychnovsky took advantage of this reactivity and achieved reductive decyanations with concomitant Birch reduction or benzyl ether cleavage [29][30][31]. An example related to the synthesis of polyene macrolides is described in Scheme 2

O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside

• Roman Sommer,
• Dirk Hauck,
• Annabelle Varrot,
• Anne Imberty,
• Markus Künzler and
• Alexander Titz

Beilstein J. Org. Chem. 2016, 12, 2828–2833, doi:10.3762/bjoc.12.282

• non-nucleophilic 1,4-dioxane or THF led to either no conversion (dioxane, Table 1, entry 4) or complete degradation and formation of various side products (THF, Table 1, entry 5). Finally, Birch reduction conditions were employed, however, without success leading to degradation of 6 (Table 1, entry 6

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• carbon dioxide [74][75] resulted in the formation of carboxylic acid 75. Birch reduction with concomitant methylation [76][77] followed by selective hydrogenation and reduction of the carboxylic acid resulted in the formation of alcohol 76. Installation of the remaining quarternary carbon center was

Stereoselective synthesis of the C79–C97 fragment of symbiodinolide

• Hiroyoshi Takamura,
• Takayuki Fujiwara,
• Isao Kadota and
• Daisuke Uemura

Beilstein J. Org. Chem. 2013, 9, 1931–1935, doi:10.3762/bjoc.9.228

• the Birch reduction to afford the trans-alkene 6, wherein the benzyl moiety was deprotected. The alkene 6 was derivatized to the spiroacetal C79–C96 fragment 7 in four steps including the benzyl protection and Sharpless asymmetric dihydroxylation (AD). Although the desired spiroacetal fragment 7 was

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• the Birch reduction [42]. The radical process is employed to create the substituted aromatic motif, which is then reduced by the dissolving metal. Scheme 19 contains one such transformation, where the intermolecular radical addition is followed by ring closure to give tetralone 94, which is easily

• converted into tricyclic derivative 95. An alkylative Birch reduction finally furnishes 96 containing an angular methyl group [43]. This strategy lends itself in principle to numerous modifications, providing access to various ring combinations and substitution patterns. The facility of introducing polar

• . Synthesis of bicyclic cyclobutane motifs. Construction of the CD rings of steroids. Rapid assembly of polyquinanes. Formation of a polycyclic structure via an allene intermediate. A polycyclic structure via the alkylative Birch reduction. Synthesis of polycyclic pyrimidines and indoline structures

Synthesis of 4” manipulated Lewis X trisaccharide analogues

• Christopher J. Moore and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2012, 8, 1134–1143, doi:10.3762/bjoc.8.126

• step under Birch reduction conditions [15][68][69][74][75]. Thus, treatment of trisaccharide 26α with sodium in liquid ammonia at −78 °C was followed by neutralization of the reaction mixture with AcOH and purification by gel permeation chromatography on a Biogel P2 column (water) to give the desired

Amine-linked diglycosides: Synthesis facilitated by the enhanced reactivity of allylic electrophiles, and glycosidase inhibition assays

• Ian Cumpstey,
• Jens Frigell,
• Elias Pershagen,
• Tashfeen Akhtar,
• Elena Moreno-Clavijo,
• Inmaculada Robina,
• Dominic S. Alonzi and
• Terry D. Butters

Beilstein J. Org. Chem. 2011, 7, 1115–1123, doi:10.3762/bjoc.7.128

• deprotection of the silyl ether in the dihydroxylation product 16 gave only a low yield of the triol 19. Subsequently, the benzyl ethers and nosylamide in 19 were cleaved under Birch reduction conditions to furnish the free Man(N4–6)Glc diglycoside 21. The other erythro configured pseudodisaccharide 15 behaved

Convergent syntheses of Le^X analogues

• An Wang,
• Jenifer Hendel and
• France-Isabelle Auzanneau

Beilstein J. Org. Chem. 2010, 6, No. 17, doi:10.3762/bjoc.6.17

• efficient and convergent preparation of these three Lex analogues. Keywords: Birch reduction; convergent synthesis; desulfurization; Lewis X; Introduction Our group is involved in the design of new anti-cancer vaccines based on the Tumor Associated Carbohydrate Antigen (TACA) dimeric Lex (dimLex) [1][2][3

• accomplished in one step and concurrently with the reduction of azido groups to the corresponding amines, using Birch reduction conditions. Thus we embarked on the one step deprotection of trisaccharides 29–32 with sodium in ammonia (Table 2). Treatment of trisaccharides 29 and 30 with sodium in liquid ammonia

• the structure of trisaccharide 1 was confirmed by HR-ESI mass spectrometry and NMR, the structure of the 6-aminohexyl glycoside 2 was confirmed by comparing its analytical data to that previously reported [31]. To our surprise, treatment of the 6-acetylthiohexyl trisaccharide 31 under Birch reduction

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• concave face of the molecule, anti to the exo-disposed benzyloxymethyl group. The standard methodology involving azide displacement gave the aziridine 84. The benzyl groups were removed using a Birch reduction and subsequent oxidation with DDQ furnished the aziridinomitosane 85 in good overall yield

Radical cascades using enantioenriched 7-azabenzonorbornenes and their applications in synthesis

• David M. Hodgson and
• Leonard H. Winning

Beilstein J. Org. Chem. 2008, 4, No. 38, doi:10.3762/bjoc.4.38

• -azabenzonorbornadienes. Oxidation (using RuO4) and Birch reduction of the 2-aza-5,6-benzonorbornenes provide access to substituted pyrrolidines and tetrahydroindenes, respectively. Keywords: asymmetric synthesis; deoxygenation; radicals; rearrangements; tandem reactions; Introduction Carbon-centred radicals have been

• -azabenzonorbornenyl framework and acid-catalysed rearrangement, reduction also presented an attractive means of modifying the carbon skeleton. Reduction of azacycle (+)-8 under standard Birch conditions [39], gave diene (+)-39 (53% yield, Scheme 11) and indane 40 (32%). Birch reduction of substituted 2

• pyrrolidine. Ring-opening–hydration–oxidation of azacycle 8. Preparation of trisubstituted pyrrolidine (+)-36. Preparation of pyrrolidine diester (+)-35 from Vince’s lactam 37. Acid-catalysed ring-opening–oxidation of azacycle (+)-8. Birch reduction of (+)-8 and 10. Supporting Information Supporting

Knorr- Rabe partial reduction of pyrroles: Application to the synthesis of indolizidine alkaloids

• Brendon S. Gourlay,
• John H. Ryan and
• Jason A. Smith

Beilstein J. Org. Chem. 2008, 4, No. 3, doi:10.1186/1860-5397-4-3

• Brendon S. Gourlay John H. Ryan Jason A. Smith School of Chemistry, University of Tasmania, Hobart, Australia CSIRO Division of Molecular and Health Technologies, Bag 10, Clayton South, Victoria, Australia 10.1186/1860-5397-4-3 Abstract Background The Birch reduction of electron rich pyrroles

• required bicyclic 3-pyrrolines and chose to explore accessing these intermediates via partial reduction of the corresponding pyrrole derivatives. These substrates were far more electron rich than those of Donohoe and thus not amenable to Birch reduction methodology. Therefore, we turned to an underutilised

• intermediate. Donohoe's approach to (±)-1-epiaustraline utilising a modified Birch reduction. Reaction conditions i) Zn, HCl (aq). Reaction conditions: i) ref. [10] ii) ref. [11] iii) Zn, conc. HCl(aq). Potential mechanism for α-ketopyrrole reduction.. Alternative reduction pathway. Catalytic hydrogenation