The Ritter reaction of terpenes. Part 2. The fenchyl system

The Ritter reaction of fenchyl alcohols 2a-f was examined. Surprisingly, in the case of alcohols 2a-d, formation of the corresponding alkenes 3 was observed. These compounds underwent, in turn, Namietkin and Wagner-Meerwein rearrangements, followed by endo-6,2-hydrogen shift to give acetamides 8 and 9, The alcohol 2e gave a mixture of hydrocarbons 11 and 12 as well as an anti acetamide 9e. For secondary ando-2-fenchol (2f) exo-isofenchyl acetamide (15) was the only product as a result of endo-6,2-hydrogen shift and subsequent reaction with acetonitrile.