(14) Some controversy over the furan-like ion structure has been raised: WH Pirkle and M. Dines, J. Amer. Chem. Soc., SO, 2318 (1968). We wish to thank Professor P. Brown for a very helpful discussion of the mass spectrum of pyrone 6. 166) fragmentation. Formation of the benzylic-type ion (m/e 109) is a transformation characteristic of alkylbenzenes, 16 and as with alkylbensenes containing side chains longer than propyl, the 0 cleavage was ...