Pummerer Synthesis of Chromanes Reveals a Competition between Cyclization and Reductive Chlorination

Org Lett. 2019 Sep 6;21(17):6903-6908. doi: 10.1021/acs.orglett.9b02520. Epub 2019 Aug 23.

Abstract

The competition between an unprecedented reductive chlorination and the Pummerer reaction was studied and applied to the synthesis of benzofused oxygen heterocycles including 3-aminochromanes and in the intramolecular chlorination of activated aromatic rings. The use of (COCl)2 as a Pummerer activator showed substantial activity, producing α-chlorinated sulfides that can undergo Pummerer-Friedel-Crafts cyclization. If the aromatic ring has electron-donating groups in position three, then the reaction follows a different pathway, yielding the reductive chlorination products, where the chlorine atom comes from a sulfonium salt.

Publication types

  • Research Support, Non-U.S. Gov't