Regioselective and enantioselective synthesis of seven-membered ring cyclic arylguanidine and urea derivatives

Cycloaddition reaction of 2-vinylpyrrolidines with carbodiimides in the presence of palladium acetate and dpppentane affords seven-membered ring cyclic arylguanidines in good yields and conversions. When 1-butyl-4-methyl-2-vinylpyrrolidine was used as a mixture of trans and cis isomers in a 4:1 ratio, and reacted with bis(2-chlorophenyl)carbodiimide , high stereoselectivity was achieved and only the trans seven-membered cyclic guanidine was obtained. A methyl group in the 4-position of the pyrrolidine ring and the chloro substituent in the ortho position of the carbodiimide may be responsible for the enhanced product ratio in favor of the trans isomer.