title: N-Heterocyclic Carbene Catalyzed Oxidative Coupling of Alkenes/α-Bromoacetophenones with Aldehydes: A Facile Entry to α,β-Epoxy Ketones.
abstract: A novel, N-heterocyclic carbene (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, first NHC-catalyzed Darzens reaction of α-bromoketones and aldehydes under mild reaction conditions has also been described. Interestingly, mechanistic studies have revealed the preferred reactivity of NHC with alkene/α-bromoketone rather than aldehydes, thus proceeding via the ketodeoxy Breslow intermediate.
authors.affiliation: Chemical Engineering and Process Development Division, National Chemical Laboratory, Pashan Road, Pune, 411008 (India).
authors.forename: Rambabu N
authors.initials: RN
authors.lastname: Reddi
authors.affiliation: Chemical Engineering and Process Development Division, National Chemical Laboratory, Pashan Road, Pune, 411008 (India).
authors.forename: Pragati K
authors.initials: PK
authors.lastname: Prasad
authors.affiliation: Chemical Engineering and Process Development Division, National Chemical Laboratory, Pashan Road, Pune, 411008 (India). a.sudalai@ncl.res.in.
authors.forename: Arumugam
authors.initials: A
authors.lastname: Sudalai
keywords: N-heterocyclic carbenes; aldehydes; epoxidation; oxidation; synthetic methods