Purines, pyrimidines, and imidazoles. Part XLIII. Halogenation of N-3-methylbut-2-enylphthalimide; new syntheses of zeatin analogues

Abstract

Halogenation of N-(3-methylbut-2-enyl)phthalimide with either N-bromo- or N-chloro-succinimide or with t-butyl hypochlorite in equimolar or greater amounts gives as the major product the N-(2-halogeno-3-methylbut-2-enyl)-phthalimide. With an excess of N-bromosuccinimide a small amount of N-(2,4-dibromo-3-bromomethylbut-2-enyl)phthalimide is obtained. Bromination of (Z)- and (E)-3-methyl-4-t-butoxybut-2-enylphthalimide with triphenylphosphine dibromide produced (Z)-4-bromo-3-methylbut-2-enylphthalimide and the corresponding E-isomer, respectively. The bromo-derivatives react readily with nucleophiles and the resulting allylphthalimides may be converted into zeatin analogues by known processes. The structures of the compounds described were confirmed by mass and n.m.r. spectra.