Chemistry of 1,3-Oxathianes. Synthesis and Conformation of 2-Substituted 1,3-Oxathianes

Article abstract of DOI:10.1021/jo00205a020

The reaction of 2-lithio-1,3-oxathiane with a variety of electrophiles including alkyl halides and carbonyl compounds affords substitution and addition products, respectively.Alkyl metal halides such as (CH3)3SiCl, (CH3)3GeCl, and (CH3)3SnCl, or alkyl metal acetate, (CH3)3PbOAc, reacted with 1,3-oxathianyl anion to give rise to the corresponding 2-(group 14)-substituted 1,3-oxathianes (4). 2-(Methylthio)- and 2-(methylseleno)-1,3-oxathianes (6b and 6c) were prepared by a similar reaction of the anion with dimethyl disulfide and dimethyl diselenide, respectively.Other1,3-oxathianes substituted with a 2-methoxy or 2-dimethylamino group at C-2 have been synthesized to investigate the orientation of heteroatoms.Examination of their 1H and 13C NMR spectra leads to the conclusion that group 14 metals and a dimethylamino group occupy the equatorial position, while methoxy and methylthio groups favor the axial disposition due to the anomeric effect.Conclusive evidence was not obtained from the available data to decide whether 2-(methylseleno)-1,3-oxathiane (6c) exhibits the anomeric effect or not.