Sequential (3 + 2) cycloaddition and (5 + n) annulation for modular synthesis of dihydrobenzoxazines, tetrahydrobenzoxazepines and tetrahydrobenzoxazocines

Abstract

A two-step method for the (3 + 2) cycloaddition of azomethine ylides followed by a double S_N2 substitution-based (5 + n) annulation is introduced for the modular synthesis of dihydrobenzoxazine, tetrahydrobenzoxazepine and tetrahydrobenzoxazocine derivatives. After a quick water wash without further purification, the (3 + 2) cycloaddition intermediates were used for the (5 + n) annulation to afford products. Green chemistry metrics analysis of the synthetic processes provided favorable results.