Stereo‐ and Site‐Selective Crotylation of Alcohol Proelectrophiles via Ruthenium‐Catalyzed Hydrogen Auto‐Transfer Mediated by Methylallene and Butadiene.

Iodide‐bound ruthenium‐JOSIPHOS complexes catalyze the redox‐neutral C−C coupling of primary alcohols with methylallene (1,2‐butadiene) or 1,3‐butadiene to form products of anti‐crotylation with good to excellent levels of diastereo‐ and enantioselectivity. Distinct from other methods, direct crotylation of primary alcohols in the presence of unprotected secondary alcohols is possible, enabling generation of spirastrellolide B (C9–C15) and leucascandrolide A (C9–C15) substructures in significantly fewer steps than previously possible. [ABSTRACT FROM AUTHOR]