Preparation of chiral 2-stannyloxazolidines and first considerations on the transacetalisation reaction mechanism

N-Protected 2-tributylstannyl-1,3-oxazolidines derived from N-monoprotected chiral beta-amino alcohols were obtained through transacetalisation of (diethoxymethyl)tributylstannane under acidic conditions. In the case of 4-substituted 2-tributylstannyl-1,3-oxazolidines, the kinetic product of the reaction was shown to be the trans isomer whatever the nature of the protective group, while the thermodynamic product was the cis isomer in the N-Ts series and the trans isomer in N-CO2R compounds. Aspects of the transacetalisation reaction are discussed along with those concerning the isomerisation of the products, allowing an interpretation of the obtained results. (C) Wiley-VCH Verlag GmbH Co.