ABSTRACT
An efficient method to selectively construct benzofuran and dihydrobenzofuro[2,3- d]oxazole derivatives has been successfully established by means of base-controlled cyclization of N-phenoxyamides with 1-[(triisopropylsilyl)ethynyl]-1,2-benziodoxol-3(1 H)-one (TIPS-EBX). N-phenoxyamides as multitasking reagents have triggered two different cascade reaction sequences. This is the first example of using TIPS-EBX for the transformation of C(sp) to either C(sp2) or C(sp3) under metal-free conditions.
ABSTRACT
Different 1,2-migrations and cyclizations of a variety of alkynylbenziodoxolones (EBXs) and amidoximes under one-base conditions are described. This process provides an efficient protocol for the divergent synthesis of two oxadiazine derivatives via switchable selectivity of EBXs controlled by simply varying the substituents of the amidoximes, which feature transition metal-free conditions, simple execution, and high chemoselectivity.