Stereoselective Synthesis of 2,6‐cis‐Tetrahydropyrans through a Tandem Allylic Oxidation/Oxa‐Michael Reaction Promoted by the gem‐Disubstituent Effect: Synthesis of (+)‐Neopeltolide Macrolactone

The minimal use of protecting groups is one highlight of a concise and efficient synthesis of (+)-neopeltolide macrolactone on the basis of the title tandem reaction and dithiane coupling reactions (see scheme). The gem-disubstituent effect of the dithiane moiety promoted the oxa-Michael reaction following allylic oxidation to ensure the efficient synthesis of the 2,6-cis-tetrahydropyran and high diastereoselectivity.