Sustainable photocatalytic synthesis of multisubstituted quinazolines and quinolines by naphthalene diimide.

Abstract

Substituted quinazolines are pharmaceutically important molecules, whose preparation from alcohol substrates are limited by precious metal, high reaction temperature and anaerobic conditions. We report herein an organophotocatalyst, naphthalene diimide (NDI) that fabricates such class of molecule in very high yield, from two different alcohols and ammonium acetate at room temperature and under aerobic atmosphere. Additionally, a three-component coupling from three different alcohols leads to 2,3-substituted quinolines in high yield, which attests to the remarkable dehydrogenating ability of the photocatalyst. This is the first use of NDI where the dehydrogenative ability of its one-electron reduced form has been exploited to execute smooth dehydrogenation reactions. A series of control experiments, Stern-Volmer analysis, EPR detection of the monoreduced NDI altogether establish the reaction mechanism and rationalizes such a strong dehydrogenation ability that leads to the preparation of heterocycles under mild condition.