A vinylogy concept driven highly diastereoselective cascade protocol towards [4,4]-carbospirocycles is developed by leveraging a spiro-annulation reaction through the thermodynamic enolate under organocatalysis.
Organocatalyzed Asymmetric 1,6-Conjugate Addition of <i>para</i>-Quinone Methides with Dicyanoolefins
作者:Xuanyi Li、Xiuyan Xu、Weiwei Wei、Aijun Lin、Hequan Yao
DOI:10.1021/acs.orglett.5b03471
日期:2016.2.5
A chiral thiourea catalyzed asymmetric 1,6-conjugate addition of para-quinone methides with dicyanoolefins has been developed. The reaction provided an efficient approach to the synthesis of chiral diarylmethine skeletons in good yields (up to 99% yield) with high diastereo- and enantioselectivity (>20:1 dr and up to 99.5:0.5 er), also on a gram scale. The preliminary mechanistic study showed that the remote stereocontrol was achieved through intermolecular hydrogen-bond interaction between the chiral thiourea catalyst and the para-quinone methides directly for the first time.