[1] Univ Buenos Aires, Fac Farm & Bioqui?m, Dept Ciencias Qui?m, RA-1113 Buenos Aires, Argentina
[2] CNR, Ist Sintesi Organ & Fotoreattivita ISOF, I-40129 Bologna, Italy
[3] Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Quim Organ, Ciudad Univ,C1428EGA, Buenos Aires, Argentina
[4] CONICET Univ Buenos Aires, Ctr Invest Hidratos Carbono, C1428EGA, Buenos Aires, Argentina