Flash vacuum pyrolysis of 2-diazo-8-oxabicyclo[3.2.1]oct-6-en-3-ones. A new method for the preparation of propadienones

Article abstract of DOI:10.1016/S0040-4039(00)88811-5

When diazoketones 3a and 3b are pyrolysed at 430°C and 10^-4 torr, they undergo loss of N₂ followed by Wolff rearrangement and loss of furan by retro Diels-Alder reaction to yield the desired propadienones 1(a,b). If argon is added to the pyrolysate mixture, these reactive compounds can be trapped under matrix isolation conditions at 22 K and observed by FTIR. Upon photolysis, 1b yields carbon monoxide and 2-butyne.