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[摘要]：Palladium-catalyzed reactions of various 2-bromo-3-exo-methylenecycloalkenes with a stabilized nucleophile were examd. When the carbocycles were nine-membered or larger, the corresponding endocyclic allenes were isolated in excellent yields. In a reaction of the eight-membered cyclic substrate, initial formation of a cycloocta-1,2-diene deriv. was detected; however, it dimerized slowly. The seven-membered carbocycle was inert to the reaction. Using a chiral Pd-catalyst, an axially chiral endocyclic allene was obtained in 65% ee. The cyclic allenes were applied to [2+2]cycloaddn. with ketenes, and the stereoselectivity was studied. |
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