Selective addition of Grignard reagents to 2,3-O-isopropylidene bis-Weinreb tartaric acid amide

Controlled addition of Grignard reagents to tartaric acid derived bis-Weinreb amide 3 provides a facile, direct entry to desymmetrized 1,4-functionalized-syn-2,3-diol intermediates 4 and to C2-symmetrical 1,4-diketones 5. The synthetic versatility of this method is exemplified by short syntheses of the natural plant growth regulator 10 and the synthetically valuable cyclooctene derivative 13.