Extending Pummerer reaction chemistry. Asymmetric synthesis of spirocyclic oxindoles via chiral indole-2-sulfoxides.
The conversion of (Ss)-3-(omega-allylsilane and silyl enol ether)indole-2-sulfoxides to spirocyclic indolenines and then to oxindoles proceeds, in favorable cases, with moderate levels of chirality transfer from sulfur to C3 of the indole core. A mechanistic model, which features either an Sn2'-like additive Pummerer sequence or a tight ion pair generated by an Sn1-like vinylogous Pummerer transform, is proposed to rationalize the sense of asymmetric induction.
Feldman
Ken S
KS
104 Chemistry Building, Chemistry Department, Pennsylvania State University, University Park, PA 16802, USA. ksf@chem.psu.edu
Karatjas
Andrew G
AG