Synthesis of 1,3,4-Oxadiazoles from Carboxylic Hydrazides and of 1,2-Oxazin-6-ones from α-(Hydroxyimino)carboxylic Esters with Keteneylidene Triphenylphosphorane

All articles of this category In a one-pot procedure 1,3,4-oxadiazoles 8 are prepared from carboxylic hydrazides 2 and keteneylidene triphenylphosphorane 1 via an untypical inter molecular Wittig olefination of a carbamate type carbonyl group. Under similar conditions, reaction of 1 and α-(hydroxyimino) carboxylic esters 9 furnishes 1,2-oxazin-6-ones 11 by a different process including an intra molecular olefination step. 1,3,4-oxadiazoles - 1,2-oxazines - phosphorus ylides - cascade reaction