Diastereoselective Synthesis of Highly Functionalized Tetrahydropyrans from the Cyclic Vinyl Acetal with Aldehydes Mediated by Lewis Acid Catalyst.

Abstract A new method for constructing substituted tetrahydropyrans from the conjunction of 6-ethylthio-3,4-dihydro-2-methoxy-2 H -pyran with aldehydes in the presence of 10 mol % SnCl 4 is described. This reaction is highly stereocontrolled and allows various functionalities to be incorporated at tetrahydropyran ring.