REACTIONS OF BENZOCYCLIC BETA-KETO-ESTERS WITH TOSYL AND 4-NITROPHENYL AZIDE - STRUCTURAL INFLUENCE OF DICARBONYL SUBSTRATE AND AZIDE REAGENT ON DISTRIBUTION OF DIAZO, AZIDE AND RING-CONTRACTION PRODUCTS

The reactions of beta-keto esters derived from 1- and 2-indanone, 1- a nd 2-tetralone, and benzosuberone with toluene-4-sulfonyl- (tosyl) and 4-nitrobenzenesulfonyl azide (PNBSA) in the presence of Et3N have bee n investigated in order to evaluate the influence of both dicarbonyl s ubstrate and azide reagent on the product distribution. With tosyl azi de the keto esters derived from both 2-benzocycloalkanones exhibit dea cylating diazo transfer, but those derived from the 1-benzocycloalkano nes undergo additional azido transfer to a significant or even exclusi ve extent. The finding is mainly explained in terms of the lesser reac tivity of the conjugate aryl ketone than alkyl ketone moiety. This wou ld discourage cyclization of the initial sulfonyltriazenyl anion-the p resumable azide precursor-to the triazoline adduct, in turn envisaged as the diazo progenitor. With PNBSA both indanones smoothly undergo di azo transfer, whereas their higher homologues lead to ring-contraction products ascribable to corresponding triazolines that curiously prefe r to suffer Favorskii-type ring fragmentation. Evidence has been obtai ned that tosyl azide acts as a azide-transfer reagent superior to PNBS A. A possible explanation of this fact is discussed. An X-ray crystal structure analysis of the phthalazine compound 18 (Ar = 4-Me-C6H4) has been performed.