REACTIONS OF 1-OXA-3-AZONIABUTATRIENE SALTS WITH 1,3-DIPOLES

Article abstract of DOI:10.1016/S0040-4020(01)89109-2

The nitrile N-oxide 4 undergoes a reversible cycloaddition to the carbonyl group of the 1-oxa-3-azoniabutatriene salts 3a-c to give the geminal dioxy substituted 2-azoniaallene salts 5a-c.Azibenzil 7 and 3a,d afford the 2-azoniaallene salts 8a,d.With the nitrone 11 the cumulene 3d reacts to yield the open-chain addition product 12.The salt 3a reacts with two equivalents of diazofluorene to give the β-lactamium salt 13, which can be hydrolyzed to afford the N-formyl-β-lactam 15.X-ray structural analyses of 5b and 8d confirm the proposed constitutions.