Silica gel-promoted synthesis of multisubstituted spiroindolenines from tryptamines and γ-chloro-α,β-unsaturated ketones
作者:Qiang-Qiang Liu、Chao Zheng、Shu-Li You
DOI:10.1016/j.tet.2020.131765
日期:2021.1
Here we report a one-pot synthesis of multisubstituted spiroindolenines from a series of tryptamine derivatives with γ-chloro-α,β-unsaturated ketones. The reaction sequence consists of base-induced condensation and silica gel-promoted intramolecular Michael addition. The target molecules are afforded in up to 90% yield with up to >20:1 diastereoselectivity.
Unlike phosphonium ylides used extensively for C═C bond formation, herein we disclose the direct use of phosphonium salts for site-selective alkylation to p-quinols via a 5-membered betaine-type intermediate. This strategy provides a novel and general approach for the synthesis of α-(m-aminoaryl) esters, amides and ketones under ambient conditions. The reaction proceeds through in situ generation of