The First Synthesis of α-Methylene Isophosphindoline Oxide

Abstract

Over the last decade the intramolecular palladium-catalyzed coupling of haloarenes and haloalkenes with alkenes has proven to be a particularly valuable route to a wide variety of the structurally demanding cyclic and polycyclic systems We wish now to demonstrate its successhl application to the synthesis of the first parent representative of the five-membered ring carbon-phosphorus heterocycles possessing exocyclic unsaturation, a class of compounds remaining to date practically unexplored The effected synthesis of the a-methylene isophosphindoline oxide I is delineated in the equation which reveals also the optimized catalytic system and the prerequisite reaction conditions Of those, the reaction temperature is the most crucial parameter as the desired product undergoes unexpectedly facile thermal cyclodimerization to the spiropolycyclic system 2 frequently even precluding the isolation of 1.