General Papers ARKIVOC 2006 (xi) 128-136
One-pot synthesis of benzyltriphenylphosphonium acetates from the
corresponding activated benzyl alcohols
Paola Hernández,a Alicia Merlino, a Alejandra Gerpe, a Williams Porcal, a Oscar E. Piro,b
Mercedes González,a,*and Hugo Cerecettoa,*
a Departamento de Química Orgánica, Fac. de Ciencias-Fac. de Química, Iguá 4225, Montevideo (11400), Universidad de la República, Uruguay bUniversidad Nacional de La Plata and Instituto IFLP(CONICET), Departamento de Física, Facultad de Ciencias Exactas, C.C. 67, (1900) La Plata, Argentina E-mail:
[email protected] ;
[email protected]
Abstract
A simple synthetic methodology for the preparation of benzyltriphenylphosphonium acetates is described. The reaction, using different benzyl alcohols substituted with an electron-donating group, involves the generation of a good leaving group and substitution with triphenylphosphine. In these cases the reactions take place with good yields. Furthermore, the obtained salts (16 and 17) have been used for the synthesis of 5-substituted benzofuroxan derivatives.
Keywords: Phosphonium acetates, benzyl alcohols, Wittig reaction
Introduction
Recently, therapeutically active benzofuroxans, such as 1 and 2 (Scheme 1), have emerged as an important class of anti-T. cruzi agents.1 The relevance in the activity of the phenylethenyl substituent and the N-oxide group to this activity was identified through QSAR studies.2 The synthetic routes that have been considered for the production of the phenylethenyl moiety are shown in Scheme 1. Among the various methods reported for the Wittig reaction we selected the mild conditions, promoted by crown ether catalysis, of the Bodens methodology.3
Continuing with this research we tried to prepare and evaluate as new anti-T. cruzi agents some analogs of 1 and 2, with R an electron-donating substituent. Our first approach involved the preparation of compound 6 (Scheme 2). In order to synthesize this derivative we planned the synthetic methodology shown in Scheme 2 where we used the conventional synthesis of the phosphonium salt 5 that involves halide nucleophilic substitution with triphenylphosphine.
ISSN 1424-6376 Page 128 ©ARKAT
