Highly chemo- and diastereoselective synthesis of substituted tetrahydropyran-4-ones via organocatalytic oxa-Diels–Alder reactions of acyclic α,β-unsaturated ketones with aldehydes
The first organocatalytic oxa-Diels–Alder reaction of acyclic α,β–unsaturated ketones with aldehydes is described. This reaction represents a highly chemo- and diastereoselective synthesis of substituted tetrahydropyran-4-ones in good yields with dr up to >95:5.
Carbonyl Umpolung Reactivity of Enals: NHC-Catalyzed Synthesis of Aldol Products via Epoxide Ring Opening
作者:Lal Yadav、Santosh Singh、Vijai Rai
DOI:10.1055/s-0029-1218563
日期:2010.1
A novel one-pot N-heterocyclic carbene catalyzed synthesis of aldol products and their application to a facile and highly cis-selective synthesis of tetrahydropyran-4-ones is reported. The protocol involves carbonyl umpolung reactivity of enals in which the carbonyl carbon attacks nucleophilically on electrophilic terminal epoxides, regioselectively, to afford aldol adducts in good to excellent yields.