Preparation of multiply protected alkylhydrazine derivatives by mitsunobu and PTC approaches

Alkylation reactions of hydrazine derivatives by Mitsunobu or PTC approaches are described. It has been shown that aminophthalimide derivatives are better acidic partners than their aminoimidodicarbonate (NBoc(2)) analogues, the presence of the phthaloyl group increasing the acidity of the sole proton and concomitantly reducing steric hindrance. Moreover, N-aminophthalimide derivatives can be efficiently converted into the corresponding N-amino-imidodicarbonates by a three-stage, one-flask procedure under very mild conditions. These procedures can also be efficiently used for the preparation of orthogonally N-alpha,N-beta-diprotected alpha-hydrazino esters. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)