One-pot synthesis of epoxides from benzyl alcohols and aldehydes

• Edwin Alfonzo,
• Jesse W. L. Mendoza and
• Aaron B. Beeler

Beilstein J. Org. Chem. 2018, 14, 2308–2312, doi:10.3762/bjoc.14.205

• for a general and operationally simple method to generate benzyl epoxides. One of the most powerful methods to access epoxides is through the Corey–Chaykovsky reaction [21] which uses sulfonium ylides and their subsequent reaction with carbonyl groups. This reaction has seen major advancement since

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• those of others. Keywords: 5-(heterocyclic)thiophenes; one-pot sequential synthesis; sulfur ylide; tetrasubstituted thiophene; Introduction Since the discovery of stable sulfonium ylides 1 in 1930 [1] and the pioneering work of several research groups during the 1960s (2 and 3) [2][3][4][5][6][7][8][9

• ], these carbene precursors have been played an important role in organic chemistry [10][11][12][13][14][15][16][17][18][19][20][21][22]. As shown in Figure 1, sulfur(IV) and sulfur(VI) ylides are stable. The stability of sulfonium ylides is determined by the electron delocalization of the carbanionic

• . Based on previous reports regarding carbene generation from sulfonium ylides [6][85][86], compounds 9a and 9b were reacted with excess MeOH (Scheme 2). Interestingly, 2-pyridyl-substituted N,S-acetal 9b only provided N,O-acetal 9ba via a 1,4-Micheal addition, whereas N,S-acetal 9a was completely

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• heterocycles using nitrosoalkenes as intermediates. An early example is the reaction of sulfonium ylides 92 with α-halo ketoximes 1 leading to isoxazolines 93 reported by Bravo [11] and Gilchrist [83] (Scheme 35). The process is believed to proceed via the generation of a nitrosoalkene intermediate (NSA

• ) followed by a formal [4 + 1]-annulation reaction with ylide (tandem Michael addition/intramolecular nucleophilic substitution of dimethylsulfide by oximate anion in intermediate 94). The addition of sulfonium ylides to nitrosoalkenes can end up not only with cyclic products, but also with α,β-unsaturated

• observed. Triphenylarsonium ylides were also studied in the reaction with nitrosoalkenes, yet lower yields of isoxazolines 93 were obtained as compared to sulfonium ylides [11]. Following the same reaction pattern, Cheng and co-workers [84] applied diazo compounds 96 instead of sulfonium ylides 92 in the

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• coworkers [60]. In particular, a range of densely functionalized heterobicyclic and carbocycles 90 were readily accessible in high yields and high stereoselectivity starting from properly functionalized sulfonium ylides 89 (Scheme 24). Computational and experimental investigations suggested the initial 20d

Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4-phthalimidocarboxylic esters derived from methionine and cysteine

• Marc Enßle,
• Stefan Buck,
• Roland Werz and
• Gerhard Maas

Beilstein J. Org. Chem. 2012, 8, 433–440, doi:10.3762/bjoc.8.49

• reaction. Keywords: α-aminoacids; carbonyl ylides; cycloaddition; α-diazo-β-ketoesters; sulfonium ylides; Introduction The synthetic potential of diazo compounds, in particular of α-diazoketones and α-diazoesters, is greatly widened by the ability of the derived carbene or metal-carbene intermediates to

• ][6][7][8] illustrate the wide range of applications. As far as sulfonium ylides are concerned, thermally induced isomerisation, that is the 1,2-shift of a substituent (Stevens rearrangement) and [2,3]-sigmatropic rearrangement of allylsulfonium ylides [9][10][11], and the use as C1 building blocks in

• epoxidation, aziridination and olefination reactions [12][13] are common reaction channels. The intramolecular formation of sulfonium ylides from α-diazocarbonyl compounds tethered with alkylthio or arylthio groups has been studied by the research groups of Davies [14], Moody [15], and West [16]. From α-diazo