The cross-aldol reaction between a ketone and an aldehyde proceeded smoothly with threo diastereoselection favorably mediated by ytterbium trifluoromethanesulfonate and tertiary amine in diethyl ether or in dichloromethane. A ytterbium enolate was trapped with chlorotrimethylsilane to afford a silyl enol ether.
ERYTHRO-SELECTIVE ALDOL CONDENSATION VIA ENAMINOSILANES
作者:Wataru Ando、Hidetoshi Tsumaki
DOI:10.1246/cl.1983.1409
日期:1983.9.5
In the presence of BF3·OEt2, enaminosilanes derived from acyclic and cyclic ketones have been shown to undergo erythro selective kinetic aldolcondensation.
A new chiral oxazaborolidine catalyst was prepared in situ from 3,5-bis(trifluoromethyl)phenylboron dichloride and N-(p-toluenesulfonyl)-(S)-tryptophan. This catalyst is much more active than Corey's original catalyst for the Mukaiyama aldol reaction of aldehydes with silyl enol ethers. The observed syn selectivities and re-face attack of silyl enol ethers on carbonyl carbon of aldehydes imply that the extended-transition state model is applicable.
Titanium silicate molecular sieve, TS-1, catalysed C–C bond formation in Mukaiyama type aldol reactions
作者:M. Sasidharan、Satya V. N. Raju、K. V. Srinivasan、Vincent Paul、R. Kumar
DOI:10.1039/cc9960000129
日期:——
The titanium silicate molecular sieve, TS-1, efficiently catalyses the formation of carbon-carbon bond in the Mukaiyama type aldol reaction of silyl enol ethers and aldehydes forming beta-hydroxy esters/aldols in high yields under heterogeneous and ambient reaction conditions.