Structural studies of thiophilic N-chloroazasteroids.

N-Chloroazasteroids form covalent S-N bonds with thiol groups and so are of interest as chemoselective irreversible binding agents for the active sites of steroid receptors and enzymes. The solid-state structures of N-chloro-3-methoxy-17-aza-D-homo-1,3,5(10)-estratrien-16-one (1), N-chloro-3-methoxy-17-aza-D-homo-1,3,5(10)-estratrien-17a-on e (2) and N-chloro-3-methoxy-16-aza-1,3,5(10)-estratrien-17-one (3) were determined to obtain information about the spatial arrangement of the N-Cl groups. Crystal data: (1) C19H24ClNO2, Mr = 333.84, orthorhombic, P2l2l2l, a = 8.0190 (3), b = 12.7175 (5), c = 16.5047 (9) A, V = 1683.2 (1) A3, Z = 4, Dx = 1.317 g cm-3, lambda(Cu K alpha) = 1.54178 A, mu = 20.9 cm-1, F(000) = 712, T = 295 K, R = 0.045 for 1786 observed reflections; (2) C19H24ClNO2, Mr = 333.84, orthorhombic, P2l2l2l, a = 10.9853 (7), b = 11.8216 (5), c = 12.9851 (9) A, V = 1686.3 (2) A3, Z = 4, Dx = 1.315 g cm-3, lambda(Cu K alpha) = 1.54178 A, mu = 20.9 cm-1, F(000) = 712, T = 295 K, R = 0.035 for 1891 observed reflections; (3) C18H22ClNO2, Mr = 319.81, monoclinic, P2l, a = 13.246 (2), b = 7.972 (2), c = 7.696 (3) A, beta = 90.24 (2) degrees, V = 812.7 (4) A3, Z = 2, Dx = 1.307 g cm-3, lambda(Cu K alpha) = 1.54178 A, mu = 21.4 cm-1, F(000) = 340, T = 295 K, R = 0.045 for 1636 observed reflections.(ABSTRACT TRUNCATED AT 250 WORDS)