An efficient, environmentally benign and unprecedented synthesis of various α-sulfenylated amides/esters has been developed under oxygen atmosphere. The reaction shows good functional group tolerance and excellent chemo/regioselectivity. All the desired products were obtained in moderate to excellent yields, even on the gram scale. Practically, the related α-thiol Weinreb amide can be readily transferred
Development of Chiral Ureates as Chiral Strong Brønsted Base Catalysts
作者:Azusa Kondoh、Sho Ishikawa、Masahiro Terada
DOI:10.1021/jacs.9b13922
日期:2020.2.26
Recently, chiralBrønsted bases having high basicity have emerged as a powerful tool in developing new catalytic enantioselective reactions. However, such chiral strong Brønsted base catalysts are still very scarce. Herein, we report the development of a chiral anionic Brønsted base having a N,N'-dialkyl ureate moiety as a basic site. Its prominent catalytic activity was demonstrated in the enantioselective
Reactions of 1-lithio-1-phenylthiomethyl- (1a) and 1-lithio-1-methylthiomethyltrimethylsilane (1b) with amides, an ester, acid anhydrides, a urea, and a carbonate are described which provide useful routes to functionalized vinylsulfides. The reaction of 1 with amides gave β-functionalized vinylsulfides, 1-dialkylamino-2-phenylthio (or methylthio)ethylenes, in 40–95% yields and the reaction could
Cu(I)/Chiral Bisoxazoline-Catalyzed Enantioselective Sommelet–Hauser Rearrangement of Sulfonium Ylides
作者:Shu-Sen Li、Jianbo Wang
DOI:10.1021/acs.joc.0c01590
日期:2020.10.2
asymmetric thia-Sommelet–Hauser rearrangement of sulfonium ylides remains a great challenge due to its multistep reaction mechanism involving metal carbene formation, proton transfer, and [2,3]-sigmatropic rearrangement. In particular, the key problem of such reactions is the differentiation of the enantiotopic lone pair electrons of sulfur, which generates the sulfonium ylide intermediate bearing chirality
Stereocontrolled Aziridination of Imines via a Sulfonium Ylide Route and a Mechanistic Study
作者:Xiao-Fang Yang、Ming-Jie Zhang、Xue-Long Hou、Li-Xin Dai
DOI:10.1021/jo0257389
日期:2002.11.1
temperature. trans-Aziridines were also obtained when imines 1 and sulfinimines 9 were reacted with N,N-dimethylacetamide-2-dimethylsulfonium bromide (7) in the presence of a base, respectively. A mechanistic study showed that the stereochemistry of these reactions was controlled by the reactivity of the imines and ylides. A higher reactivity of imines and ylides favors the formation of cis-aziridines, whereas