A novel bridged-A-ring steroid

Abstract

Abstract.2,10-Ethano-10-norandrost-4-ene-3,17-dione, C2oH2602, Mr= 298.43, orthorhombic, P2~2121, a--7-566 (3), b= 11.478 (7), c= 18.681 (7)A, V= 1622.5(13)A 3, Z=4, D m (flotation in aqueous ZnC12) --1.21 (2), D x = 1.222 Mg m -3, 2(Mo Ka--) = 0.71073 A, #= 0.0716 mm -1, F(000) = 648, T= 293 K, R --0.038, wR -0.052 for 1629 observations. The title molecule was prepared as part of synthetic efforts in the design of inhibitors for steroid 5a-reductase. Based upon a desire to lift the A ring in the fl direction, relative to the parent androst-4-ene-3,17-dione, this novel steroid contains an ethano bridge between atoms C(2) and C(10). The A ring displays a highly distorted l~t-sofa conformation with C(1) disposed 0.844 (2)/k below the plane defined by atoms C(2), C(3), C(4), C(5) and C(10). Mirror symmetry is dominant in the A ring with ACs ~ = 9.0. The remainder of the steroid nucleus displays a normal conformation including a flattened Met-envelope for the D ring. Relative to androst-4-ene-3,17-dione the position of atom 0(3) is lifted 0.151 A toward the fl face. The observed structure is consistent with molecular modelhag predictions.