The pyrazolines (12),(18),(21),(26) and (32), prepared by addition of diazomethane to alkyl cyclopropene-1-carboxylates or to 1-trimethylsilylcyclopropenes respectively, rearrange at 20 to 70° C to diazo-compounds (14),(19),(23),(28) and (36). Pyrazolines (22) and (33) are unchanged under these conditions. Catalytic decomposition of the diazo-compounds is highly dependent on the nature of the substituents and on the catalyst, leading to ...
