Generation and reactions of a 3-furylcarbene and of an isoxazol-4-yl-carbene

Abstract

2,5-Diphenylfuran-3-carbaldehyde reacted with 1-amino-trans-2,3-diphenylaziridine to give the hydrazone (6), which on photolysis or pyrolysis gave products derived from the 3-furylcarbene (5). In contrast to reactions reported for 2-furylcarbenes there is no evidence of ring-opening in the 3-furylcarbene, and the reactions observed (insertion and cycloaddition) are those of a normal arylcarbene. A similar investigation of the corresponding hydrazone (8) from an isoxazole-4-carbaldehyde shows that ring cleavage does occur on pyrolysis. The relevance of these observations to a possible mechanism for the thermal decomposition of 3-phenylprop-2-ynal is discussed.