Asymmetric Synthesis of 1,3‐Butadienyl‐2‐carbinols by the Homoallenylboration of Aldehydes with a Chiral Phosphoric Acid Catalyst |
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| Authors: | Prof?Dr Yiyong Huang Xing Yang Zongchao Lv Chen Cai Cheng Kai Prof?Dr Yong Pei Dr Yu Feng |
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| Affiliation: | 1. Department of Chemistry, School of Chemistry, Chemical, Engineering and Life Science, Wuhan University of Technology, Wuhan 430070 (P.R. China);2. Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences (P.R. China);3. Department of Chemistry, Xiangtan University (P.R. China) |
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| Abstract: | Asymmetric C(sp)? C(sp2) 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. |
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| Keywords: | allylic alcohols asymmetric dienylation boron enantioselectivity organocatalysis |
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