pyridine can remove within a few hours methoxy-, allyloxy-, and benzyloxycarbonyl groups from saccharidic carbinols under conditions compatible with the maintenance of acyl groups. Addition of a stoichiometric excess of acetic acid to the reaction mixture minimizes or even suppresses intramolecular transesterifications. The procedure broadens the scope of some alkoxycarbonyl groups in organic synthesis
Alkoxycarbonyl groups can be readily installed on carbohydrates by reaction with the corresponding chloroformates in the presence of TMEDA at low temperature. The mild reaction conditions can be modulated to attain regioselective protections. (C) 2000 Elsevier Science Ltd. Ail rights reserved.