Intramolecular biaryl coupling reaction of benzyl benzoate and phenyl benzoate derivatives, and its application to the formal synthesis of (−)-steganone

Construction of the biaryl moiety of stegane and related compounds through an intramolecular biaryl coupling reaction is described. Undesired products were obtained by the intramolecular coupling reaction of benzyl benzoates (8, 13, and 14) because of their steric and electrostatic properties, and only that of phenyl benzoates (26b and 26c) afforded the desired biaryl lactones in good yields. An asymmetric formal synthesis of the title compound has been achieved using an enantioselective lactone-opening reaction followed by a four-step conversion to the known compound.