N-Heterocyclic Carbene Catalyzed Oxidative Coupling of Alkenes/ α-Bromoacetophenones with Aldehydes: A Facile Entry to α,β-Epoxy Ketones
作者:Rambabu N. Reddi、Pragati K. Prasad、Arumugam Sudalai
DOI:10.1002/anie.201507363
日期:2015.11.16
A novel, N‐heterocycliccarbene (NHC) catalyzed direct oxidative coupling of styrenes with aldehydes has been described for the synthesis of α,β‐epoxy ketones in good yields. This unprecedented regioselective oxidative coupling employs NBS/DBU/DMSO (DBU=1,8‐diazabicyclo [5.4. 0] undec‐7‐ene, DMSO=dimethylsulfoxide, NBS=N‐bromosuccinimide) as an oxidative system at ambient conditions. Additionally,
Catalytic asymmetric Darzens condensation under phase-transfer-catalyzed conditions
作者:Shigeru Arai、Takayuki Shioiri
DOI:10.1016/s0040-4039(98)00081-1
日期:1998.4
The catalytic asymmetric Darzenscondensation promoted by the quaternary ammonium salt (PTC A) derived from cinchonine as a phase-transfer catalyst is described. Treatment of phenacyl chloride with various aldehydes under mild reaction conditions afforded the corresponding desired product in good yield with good to moderate enantiomeric excess.
Catalytic asymmetric Darzens reaction promoted by a chiral phase-transfer catalyst derived from cinchonine is described. The desired α,β-epoxy ketones were obtained by use of α-chloro acyclic and cyclic ketones as substrates with moderate to high enantiomeric excesses under mild reaction conditions. This methodology can be quite an effective protocol for practical asymmetric synthesis.