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Rhodium‐Catalyzed Regioselective Synthesis of Isoindolium Salts from 2‐Arylpyridines and Alkenes in Aqueous Medium under Oxygen
Author(s) -
Upadhyay Nitinkumar Satyadev,
Jayakumar Jayachandran,
Cheng ChienHong
Publication year - 2016
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201600452
Subject(s) - chemistry , alkene , regioselectivity , rhodium , intramolecular force , deprotonation , michael reaction , catalysis , aqueous solution , medicinal chemistry , salt (chemistry) , organic chemistry , ion
A highly regioselective synthesis of pyrido[2,1‐ a ]isoindolium salts from 2‐arylpyridines and two equivalents of electron‐deficient alkenes catalyzed by rhodium is demonstrated. The reaction was carried out in aqueous medium at 110 °C using inexpensive oxygen as oxidant. Reverse aza‐Michael addition of the isoindolium salt occurs when the salt was treated with base to give a β‐disubstituted alkene product. A reaction mechanism involving an ortho C–H olefination of 2‐arylpyridine by alkene, intramolecular aza‐Michael addition, deprotonation at the β‐carbon of the alkene fragment followed by another Michael addition to give the final product is proposed.