Photolysis of dipropyldiazirine and trapping of dipropylcarbene with piperidine

Article abstract of DOI:10.1016/S0040-4039(99)00356-1

Photolysis (350 nm) of dipropyldiazirine in methylene chloride at 4°C produces a mixture of E and Z 3-heptene in 81% yield in an E/Z ratio of 1.8. Tetrapropylazine was formed in less than 5% yield. Photolysis of dipropyldiazirine in the presence of piperidine leads to the formation of a carbene-amine adduct. In the presence of 0.06 M piperidine the yield of adduct is 48%, the yield of E and Z 3-heptene is 47% and the E/Z ratio of 3- heptenes is 1.1. The results show that heptene is formed by three pathways. One pathway involves dipropylcarbene formed directly from the diazirine, the other pathways are attributed to ionic and photochemical reactions of 4- diazoheptane and to the excited state of the diazirine precursor. Dipropylcarbene can be easily intercepted with a simple trap. The yield of this process is limited by the efficiency with which the precursor forms the carbene.