Enantioselective Synthesis of β-Quaternary Carbon-Containing Chromanes and 3,4-Dihydropyrans via Cu-Catalyzed Intramolecular C–O Bond Formation
作者:Jinhui Cai、Zhen-Kai Wang、Muhammad Usman、Zhi-Wu Lu、Xu-Dong Hu、Wen-Bo Liu
DOI:10.1021/acs.orglett.9b03549
日期:2019.11.1
A copper-catalyzed efficient enantioselective construction of chiral quaternarycarbon-containing chromanes and 3,4-dihydropyrans is reported. The desymmetric C-O coupling is enabled by a chiral dimethylcyclohexane-1,2-diamine ligand and provides the desired products in good yields with high enantioselectivities. This method presents a broad substrate scope and is applicable to diversely substituted
Z-allylic dibromides regio- and stereoselectively prepared were reacted with the sodium enolate of ethyl acetoacetate or di(α-ethoxyvinyl)cuprate to yield, after hydrolysis, and decarboxylation in the case where the enolate of ethylacetoacetate was the nucleophile, the corresponding ketones. After reduction and bromination, the products were converted into the appropriate organometallic compounds and