Palladium(II)-Catalyzed Highly Regio- and Diastereoselective Cyclization of Difunctional Allylic N-Tosylcarbamates. A Convenient Synthesis of Optically Active 4-Vinyl-2-oxazolidinones and Total Synthesis of 1,4-Dideoxy-1,4-imino-l-xylitol

A Pd(II)-catalyzed cyclization of difunctional allylic N-tosyl carbamates in the presence of halide ions was developed with high regio- and diastereoselectivity. The reaction involves aminopalladation of alkene and beta-heteroatom elimination to regenerate Pd(II) species. When the readily available homochiral alcohols were used as substrates, highly optically active 4-vinyl-2-oxazolidinones were easily obtained. The utility of this method was exemplified by the convenient synthesis of 1,4-dideoxy-1,4-imino-L-xylitol.