Recycling Catalyst as Reactant: A Sustainable Strategy To Improve Atom Efficiency of Organocatalytic Tandem Reactions.

A sustainable strategy by internally recycling an organocatalyst as a reactant in a downstream reaction to improve the atom efficiency of organocatalytic tandem reactions is described. Specifically, a one-pot tandem Cloke-Wilson/Boulton-Katritzky reaction of cyclopropylketones with a hydroxylamine has been developed for the synthesis of fully substituted isoxazoles, in which the hydroxylamine serves as both an upstream catalyst and a downstream reactant.