Synthetic studies on the immunosuppressive agent FK-506: Enantioselective synthesis of a C22C34 fragment

Abstract The C28C32 cyclohexyl group of the natural product, FK-506, was prepared enantioselectively from the iodolactone by replacement of iodide with retention of configuration . The C27C28 trisubstituted olefin was introduced stereoselectively via a classical aldol/elimination sequence employing titanium enolate methodology. Elaboration of this chemistry has led to a synthesis of a C22C34 fragment of the natural product.