Structure of [(1s)-1-[(1's)-3'-oxocyclohexyl]-3,3-dimethoxy-1-propyl] [(1s,2s,3r)-1,3,7,7-tetramethyl-2-hydroxy-3-bicyclo[2.2.1]heptyl] Sulfone

C22H38O6S, M(r) = 430.60, monoclinic, P2(1), a = 6.922 (2), b = 16.733 (2), c = 10.070 (3) angstrom, beta = 96.88 (2)-degrees, V = 1158.0 (4) angstrom 3, Z = 2, D(x) = 1.24 g cm-3, Cu K-alpha, lambda = 1.54178 angstrom, mu = 14.9 cm-1, F(000) = 468, T = 291 K, R = 0.050 for 3558 observed reflections. The development of methods for the construction of five-membered carbocycles is a topic of current interest as a result of the ubiquitous occurrence of such rings in many biologically active products. We have recently developed [De Lombaert, Nemery, Roekens, Carretero, Kimmel & Ghosez (1986). Tetrahedron Lett. 27, 5099-5102] a novel two-step (3 + 2) annulation yielding highly functionalized fused cyclopentanones. We are now developing an enantioselective version of this sequence. In this context we have studied the asymmetric Michael addition of a chiral homoenolate to cyclohexenone from which the title compound was obtained in an optically pure crystalline form. The present X-ray crystallographic study establishes unambiguously the absolute stereochemistry of the title compound and the precursor homoenolate.