The addition of chlorosulfonyl isocyanate to allenea (2, 4-dimethyl-2, 3-pentadiene, 2-methyl- 2, 3-pentadiene, 2, 3-pentadiene, 3-methyl-l, a-butadiene, pentamethyleneallene, 1, 3- diphenylpropadiene, phenylpropadiene, and cyclononadiene) has been studied. In all cases, initial electrophilic attack occurred at the central carbon atom of the allenic system to produce, in the transition state, an allyl-type stabilized carbonium ion. Structures of the N- ...