Asymmetric Synthesis of 1,3-Butadienyl-2-carbinols by the Homoallenylboration of Aldehydes with a Chiral Phosphoric Acid Catalyst.
Asymmetric C(sp)-C(sp(2)) bond formation to give enantiomerically enriched 1,3-butadienyl-2-carbinols occurred through a homoallenylboration reaction between a 2,3-dienylboronic ester and aldehydes under the catalysis of a chiral phosphoric acid (CPA). A diverse range of enantiomerically enriched butadiene-substituted secondary alcohols with aryl, heterocyclic, and aliphatic substituents were synthesized in very high yield with high enantioselectivity. Preliminary density functional theory (DFT) calculations suggest that the reaction proceeds via a cyclic six-membered chairlike transition state with essential hydrogen-bond activation in the allene reagent. The catalytic reaction was amenable to the gram-scale synthesis of a chiral alkyl butadienyl adduct, which was converted into an interesting optically pure compound bearing a benzo-fused spirocyclic cyclopentenone framework.
Department of Chemistry, School of Chemistry, Chemical, Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (P.R. China). huangyy@whut.edu.cn.|Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences (P.R. China). huangyy@whut.edu.cn.
Yiyong
Y
Huang
Department of Chemistry, School of Chemistry, Chemical, Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (P.R. China).
Xing
X
Yang
Department of Chemistry, School of Chemistry, Chemical, Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (P.R. China).
Zongchao
Z
Lv
Department of Chemistry, School of Chemistry, Chemical, Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (P.R. China).
Chen
C
Cai
Department of Chemistry, School of Chemistry, Chemical, Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (P.R. China).
Cheng
C
Kai
Department of Chemistry, Xiangtan University (P.R. China). ypnku78@gmail.com.
Yong
Y
Pei
Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences (P.R. China).
Yu
Y
Feng
allylic alcohols; asymmetric dienylation; boron; enantioselectivity; organocatalysis