Formation of spiro[1H-indene-1,2′(3′H)-1,3,4-thiadiazoles] in the cycloaddition of 2-dialkylaminoindenes to dehydrodithizone; X-ray crystal structure of 3′-phenyl-5′-phenylazo-2-pyrrolidino-spiro-[1H-indene-1,2′(3′H)-1,3,4-thiadiazole]

Abstract

Addition of 2-pyrrolidinoindene to dehydro-dithizone proceeds with loss of hydrogen to give a novel type of product, 3′phenyl-5′phenylazo-2-pyrrolidino-spiro[1H-indane-1,2′(3′H)-1,3,4-thiadiazole], whose constitution was determined by single crystal X-ray structure analysis; the formation of this and analogus compounds from 2-piperidino- and 2-morpholino-indene is thought to occur via the acyclic valency tautomer of dehydrodithizone.