Stereoselective Synthesis of<i>trans</i>-2,5-Disubstituted Tetrahydrofurans<i>via</i>the Lewis Acid Mediated Reduction of Cyclic Hemiketals with Triphenylsilane
An efficient method for the synthesis of trans-2,5-disubstituted tetrahydrofuran derivatives has been developed. Dithioacetal-functionalized cyclic hemiketals are reduced by triphenylsilane (Ph3SiH) in the presence of TiCl4 to afford the corresponding trans-2,5-disubstituted tetrahydrofuran derivatives in good yield and high stereoselectivity. Asymmetrical synthesis of (2S,5S) disubstituted tetrahydrofuran