A two-step synthesis of allylic syn 1,3-diols via an intramolecular oxa-Michael reaction followed by a modified Julia olefination

A two-step process for the synthesis of allylic syn 1,3-diols is developed. An intramolecular oxa-Michael reaction onto vinyl heteroaromatic sulfones allows the diastereoselective formation of 1-sulfonyl 2,4-diols protected as benzylidene acetals. These sulfones are then engaged in a modified Julia olefination to furnish the olefins contiguous to the benzylidene acetal ring with good E/Z selectivity.