Heck reaction
L-Selectride reduction of enone 34 gave ketone 35. The ketone was converted into vinyl triflate 36 using phenyl triflimide and potassium hexamethyldisilazide in tetrahydrofuran at −78 °C. This vinyl triflate was one of the functional groups required for the Heck reaction. For the generation of the other reactive group the acetal group was removed to give aldehyde 37 which was subsequently converted to the terminal alkene 38 in a Wittig reaction involving methylenetriphenylphosphorane. The intramolecular Heck reaction involved tetrakis(triphenylphosphine)palladium(0) and potassium carbonate in acetonitrile at reflux to give diene 39 and to complete the formation of the B ring.