A New Indole Synthesis Promoted by Metal Triflates

Abstract

Abstract A new synthesis of 4‐ and 7‐ carbon ‐substituted indoles is described. The overall sequence involves the addition of a nitrile oxide to 1 carboethoxy‐2‐(or 3‐) allylpyrrole, hydrogenation of the intermediate isoxazoline to β ‐hydroxy ketone and cyclization of the ketol using magnesium or zinc triflate to the substituted indole. This new indole‐forming strategy can also accommodate the introduction of oxygen functionality into the indole 6‐position. Possible mechanistic aspects of the reaction are detailed.