106434-82-6

A mCPBA-mediated, metal-free, intramolecular dioxygenation reaction of unactivated alkenes is reported. In the presence of m-chlorobenzoic peracid, different unsaturated amide substrates could be cyclized via epoxide intermediates, producing the corresponding 5-imino-2-tetrahydrofuranyl methanol products in up to 94% yield at room temperature.

1-(2-Propenyl)- (10a), 1-(2-methyl-2-propenyl)- (10b), and 1-(3-butenyl)cyclopropanediazonium ions (35) have been generated by alkaline cleavage of the analogous nitrosocarbamates in methanol.Their major reaction paths are cyclopropyl-allyl tranformation (67 - 81percent), elimination to give alkylidenecyclopropanes (13 - 21percent), nucleophilic displacement (4 - 6percent), and 1,2-H shift (1 - 5percent).Participation of the double bond with formation of spirocyclic products was found to be small (0.5 - 1.2percent) with 10a, b and negligible with 35.The 2-methylene-5-hexenyl cations (39) arising from 35 underwent cyclization (intramolecular electrophilic addition, 39 --> 42) in competition with nucleophilic capture, but did not undergo a degenerate Cope rearrangement (39 39').