three-component coupling of acyl fluorides, silyl enol ethers, and alkynoates. The key to the success of the reaction is the formal transmetalation between pentacoordinate P(V) species (i.e., fluorophosphorane) and a silyl enol ether, which allows for C–C bond formation between the polarity-mismatched sites. The bond formation that cannot be attained even by transition metal catalysis is accomplished
Chiral Brønsted Acid as a True Catalyst: Asymmetric Mukaiyama Aldol and Hosomi–Sakurai Allylation Reactions
作者:Masahiro Sai、Hisashi Yamamoto
DOI:10.1021/jacs.5b04168
日期:2015.6.10
diastereo- and enantioselective Mukaiyama aldol reaction catalyzed by a new chiral Brønsted acid, N-(perfluorooctanesulfonyl)thiophosphoramide, is described. The perfluorooctyl substituent on the sulfonyl group of the catalyst plays an essential role in the stereoselection. The catalyst also allows the asymmetric Hosomi-Sakurai allylation, which has been considerably challenging due to the low reactivity of
The palladium catalyzed cross-coupling reaction of thiolesters with bis(iodozincio)methane or 1,1-bis(iodozincio)ethane gave Reformatsky-type enolates. They can react with some electrophiles to give the corresponding adducts and were also trapped by silylation reagents to afford silyl enol ethers. As the method applicable to the thiolester carrying ketone moiety, it afforded zinc enolates carrying
reaction of aryldiazonium tetrafluoroborates and sulfur dioxide with silyl enolether under catalyst‐ and additive‐free conditions has been realized. This reaction proceeds efficiently at roomtemperature and goes to completion in half an hour. During the reaction process, aryldiazonium tetrafluoroborate is treated with DABCO⋅(SO2)2 (DABCO=1,4‐diazabicyclo[2.2.2]octane) to provide a sulfonyl radical as