A new way toward Z.alpha.,.beta. unsaturated esters: a pyrethroid application
摘要:
Use of the stereospecific condensation of beta-carbalkoxysulfones with aldehydes, followed by the stereospecific reduction of the afforded sulfonyl acrylate with sodium dithionite allows us to propose this method as a new way to prepare Z alpha,beta unsaturated esters. Steric hindrance seems to be the reason for the selectivity of the reduction and the mechanism was proved, by X-ray of an intermediate, to be a cis Michael addition of HSO2-, followed by an anti elimination of SO2 and the sulfinate group. This method discovered in the pyrethroid series for the synthesis of acrinathrin 1 could have general application.
of S-tert-butyl-beta-(trifluoromethyl)isocysteine have been synthesized stereoselectively by the sequential reactions of trifluoroacetimidoyl chloride with the lithium enolate of tert-butyl alpha-tert-butylthioacetate, followed by the diastereoselective reduction of the imino group with sodium borohydride in the presence of zinc(II) or di(ethylene glycol) dimethyl ether, and finally by the deprotection
D The present invention relates to ion pair catalysts (I) comprising the cationic bisguanidinium ligand (A) and diperoxomolybdate anion (B). The present invention also relates to ion pair catalysts (III) comprising the cationic bisguanidinium ligand (C) and peroxotungstate anion (D). It further relates to the use of the said catalysts in the manufacture of enantiomerically enriched sulfoxides.
D 本发明涉及由阳离子双胍配体(A)和二氧钼酸阴离子(B)组成的离子对催化剂(I)。本发明还涉及由阳离子双胍配体(C)和过氧钨酸盐阴离子(D)组成的离子对催化剂(III)。本发明还涉及上述催化剂在制造对映体富集的硫氧化物中的用途。
Preparation of Asymmetric Phase-transfer Catalyst, 1,4-Bis((4S,5S)-1,3-bis(3,5-di-tert-butylbenzyl)-4,5-diphenylimidazolidin-2-ylidene)piperazine-1,4-diium chloride
作者:Esther Cai Xia Ang
DOI:10.15227/orgsyn.097.0274
日期:——
Kamata,S. et al., Synthetic Communications, 1973, vol. 3, p. 265 - 272