Synthesis of carbohydrate-derived (Z)-vinyl halides and silanes: Samarium-promoted stereoselective 1,2-elimination on sugar-derived α-halomethylcarbinol acetates.

Abstract A general and highly selective method for the synthesis of carbohydrate-derived ( Z )-vinyl halides and silanes is described. This reaction takes place through a β-elimination process of sugar-derived α-halomethylcarbinol acetates promoted by samarium diiodide. Starting materials have been easily prepared in two steps consisting in an initial addition of halomethyllithium compounds to the corresponding galactose-derived aldehyde, followed by acetylation. A mechanism that explains both the formation of ( Z )-vinyl derivatives and its selectivity is proposed. Finally, the synthetic usefulness of these compounds has been applied in cross-coupling reactions with ethynyl benzene towards the formation of selected enyne derivatives. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]