The dipolar route to naphtho[2,1-c]isoxazoles from the Baylis-Hillman adducts of 2-alkynylbenzaldehydes

摘要

A new synthesis of 4-carbomethoxynaphtho[2,1-c]isoxazoles 4a-d from methyl 3-(alkynylphenyl)-2-nitromethyl-2-propenoates 2a-d by the intramolecular nitrile oxide cycloaddition is described. The latter are readily obtained from 2-alkynylbenzaldehydes through the Baylis-Hillman adduct acetates 1a-d followed by nucleophilic substitution of nitrite anion.