title: C(2)-Symmetric dialkoxyphosphoramide and dialkoxythiophosphoramide derivatives of (1R, 2R)-1,2-diaminocyclohexane as chiral ligands for the titanium(IV) alkoxide-promoted asymmetric addition reactions of diethylzinc to arylaldehydes.
abstract: C(2)-Symmetric chiral diethoxyphosphoramide 4, diethoxythiophosphoramide 5, and diisopropoxyphosphoramide 6 of (1R, 2R)-1,2-diaminocyclohexane were prepared by the reactions of diethoxyphosphinic chloride, diethoxythiophosphinic chloride, and diisopropoxyphosphinic chloride with (1R, 2R)-1,2-diaminocyclohexane, respectively. They were used as catalytic chiral ligands in the asymmetric addition reactions of diethylzinc to aldehydes in the presence of titanium(IV) isopropoxide to give the corresponding sec-alcohols with 43-70% ee. Chiral ligands 4 and 5 gave the sec-alcohols with opposite absolute configuration.
authors.affiliation: State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China. Mshi@pub.sioc.ac.cn
authors.forename: Min
authors.initials: M
authors.lastname: Shi
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Wu
authors.forename: Guobin
authors.initials: G
authors.lastname: Rong