Stereoselective syntheses of 2-methyl-1,3-diol acetals via Re-catalyzed [1,3]-allylic alcohol transposition.

Rhenium-catalyzed stereoselective transposition of allylic alcohols is reported. In the presence of 1 mol% of Re 2 O 7 , ( E )- or ( Z )-δ-hydroxymethyl- anti -homoallylic alcohols were converted into the acetals of 2-methyl-1,3- syn -diols with excellent diastereoselectivities. 1,3- syn -Diol acetals can also be synthesized from ( E )-δ-hydroxymethyl- syn -homoallylic alcohols.