DIAZO TRANSFER-REACTIONS OF TOSYL AZIDE WITH CARBOCYCLIC BETA-KETO-ESTERS - PRODUCTION AND DECOMPOSITION OF RING-OPENED N-TOSYLCARBAMOYL-SUBSTITUTED ALPHA-DIAZO ESTERS

The diazo transfer reaction of tosyl azide 1 with methyl 2-oxocyclopen tanecarboxylate 2a, ethyl 2-oxocyclohexanecarboxylate 2b and methyl 2- oxocycloheptanecarboxylate 2c, in the presence of triethylamine, gives ring-opened diazo amido esters 3a-c in fairly high yields. Similar re action with ethyl 2-oxocyclooctanecarboxylate 2d and methyl camphor-3- carboxylate 2e also leads to the respective diazo esters 3d,e but acco mpanied by the corresponding azido transfer products 6, 7 to a signifi cant (or major) extent, The thermal, photochemical and rhodium(II) ace tate-catalysed decomposition of the novel diazocarbonyl compounds 3a-e has been examined. The results show that intramolecular cyclization o nto the N-tosylcarbamoyl substituent can smoothly take place provided that it gives rise to a six-membered ring ylide or diazonium betaine i ntermediate, Otherwise, B-hydride elimination by an intermediate carbe ne or rhodium-carbenoid becomes the preferred, if not exclusive, decom position mode, However, unusual behaviour is encountered with the diaz o amido ester 3d in that its rhodium(II)-induced decomposition results in the preferential formation of the alpha-hydroxy ester 19.