Enantioselective Synthesis of (+)-Crocacin C. An Example of a Highly Challenging Mismatched Double Asymmetric 6-Stannylcrotylboration Reaction

A concise, enantioselective synthesis of (+)-crocacin C is described, featuring a highly diastereoselective mismatched double asymmetric delta-stannylcrotylboration of the stereochemically demanding chiral aldehyde 9 with the bifunctional crotylborane reagent (S)-E-10. The total synthesis of (+)-crocacin C was accomplished in seven steps (longest linear sequence) starting from commercially available precursors.