title: Asymmetric borylation of α,β-unsaturated esters catalyzed by novel ring expanded N-heterocyclic carbenes based on chiral 3,4-dihydro-quinazolinium compounds.
abstract: A series of chiral 6-membered ring N-heterocyclic carbene (NHC) precursors based on 3,4-dihydro-quinazoline were synthesized with overall yields of 54-62%. NHCs generated from these precursors show excellent asymmetric catalytic properties for borylation of α,β-unsaturated esters with enantioselectivity of up to 93% with a catalyst content of only 1 mol%.
authors.affiliation: College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, 333 Longteng Road, Shanghai, China. sungaris@gmail.com.
authors.forename: Liliang
authors.initials: L
authors.lastname: Huang
authors.forename: Yong
authors.initials: Y
authors.lastname: Cao
authors.forename: Manping
authors.initials: M
authors.lastname: Zhao
authors.forename: Zhongfeng
authors.initials: Z
authors.lastname: Tang
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Sun