S. Thamotharan

16-(4-Isopropylbenzylidene)androst-4-ene-3,17-dione.

In the title compound, C(29)H(36)O(2), the outer cyclohexene ring of the steroid nucleus has a conformation that lies about half-way between a half-chair and an envelope, while the central and outer cyclohexane rings of the steroid nucleus have slightly distorted chair conformations. The steroidal cyclopentane ring adopts a 13beta,14alpha-half-chair conformation. The benzylidene moiety has an E configuration with respect to the carbonyl group on the cyclopentane ring. The dihedral angle between the mean planes of the steroid nucleus and the benzylidene moiety is 35.54 (9) degrees. The packing of the molecules is assumed to be dictated mainly by weak intermolecular C-H.O interactions.

16‐(3‐Pyridyl­methyl­ene)­androst‐4‐ene‐3,17‐dione

In the title compound, C25H29NO2, ring A adopts a slightly distorted half-chair conformation, while rings B and C are in chair conformations. The five-membered ring D adopts a 13β,14α-half-chair conformation. The 3-pyridyl ring has an E configuration with respect to the carbonyl group at position 17. The crystal structure is stabilized by weak intra- and intermolecular C—H⋯O interactions and van der Waals forces.

N-(4-Acetyl­phenyl)-N′-[(4-sydnon-3-yl)­phenyl]­urea di­methyl­form­amide solvate

In the title compound, C17H14N4O4·C3H7NO, the dihedral angle between the planes of the sydnone ring and the attached benzene ring is 13.56 (8)°. The benzene rings are inclined at an angle of 21.02 (8)° with respect to one another. In the solid state, intermolecular N—H⋯O hydrogen bonds and weak intermolecular C—H⋯O interactions are observed.

N‐(2‐Naphthyl­oxy­methyl­carbonyl)­pyrrolidine

Institute of Organic Chemistry, Universityof Zu¨rich, Winterthurerstrasse 190, CH-8057Zu¨rich, Switzerland† DeceasedCorrespondence e-mail: vpsarati@yahoo.comKey indicatorsSingle-crystal X-ray studyT = 160 KMean ˙(C–C) = 0.002 A˚R factor = 0.052wR factor = 0.144Data-to-parameter ratio = 21.4For details of how these key indicators wereautomatically derived from the article, seehttp://journals.iucr.org/e.# 2003 International Union of CrystallographyPrinted in Great Britain – all rights reserved

17a‐Allyl‐3β‐pyrrolidino‐17a‐aza‐d‐homoandrost‐5‐ene monohydrate

The title compound, C26H42N2·H2O, a homoandrost-5-ene, contains four fused six-membered rings. Rings A, C and D adopt chair conformations, while ring B adopts an 8β,9α-half-chair conformation.

Methyl [8-(3,5-di­methyl­pyrazol-1-yl­methyl)-4-methyl-2-oxo-2H-chromen-7-yl­oxy]­acetate 0.19-hydrate

In the title compound, C19H20N2O5·0.19H2O, the coumarin moiety is oriented almost perpendicular to the plane of the pyrazole ring. The crystal structure is stabilized by weak intermolecular C—H⋯π interactions.

An aza-steroidal [17,16-c]pyrazole derivative: 2'-(p-fluorophenyl)-17a-aza-2'H-pyrazolo[4',3':16,17]-D-homoandrost-4-en-3-one.

The asymmetric unit of the title compound, C(26)H(30)FN(3)O, contains two crystallographically independent molecules, the core skeletons of which have the same absolute configuration and almost identical conformations, except for differences in the orientation of the p-fluorophenyl ring. The tetrahydropyridine ring adopts a half-chair conformation, while the cyclohexenone ring has a slightly distorted envelope conformation. The cyclohexane rings have chair conformations, sometimes slightly distorted. Intermolecular N-H.O, N-H.N and C-H.F interactions and an intramolecular C-H.N interaction are observed.

2′-(4-Fluoro­phenyl)-[1,2,3]­triazolo[4′,5′:16,17]­androst-5-en-3β-ol methanol hemisolvate

The asymmetric unit of the title compound, C(25)H(30)FN(3)O.0.5CH(3)OH, contains four symmetry-independent steroid and two methanol molecules. The conformations of the independent steroid molecules are very similar. Intermolecular O-H.O hydrogen bonds create two independent chains, each of which links two of the independent steroid molecules plus one methanol molecule via a co-operative O-H.O-H.O-H pattern. Intermolecular C-H.O and C-H.F interactions are also observed.

1-(2-(4-Nitrophenoxy)acetyl)pyrrolidin-2-one: an antiamnesic agent

The title compound, C(12)H(12)N(2)O(5), is a potential antiamnesic agent. The pyrrolidinone ring has an envelope conformation, and the central moiety is almost coplanar with the planes of the phenyl and pyrrolidinone rings. In the crystal structure, weak intermolecular C--H...O interactions link the molecules into a complex network that can be described by R(2)(2)(X) rings (X = 16, 20 and 26) and a C(12) chain.

Hydrogen-bonded dimers of 1,8,10-trihydroxy-10-(prop-2-enyl)anthracen-9(10H)-one: S(6), R(2)(1)(10) and R(2)(2)(14) motifs.

The central ring of the anthrone system in the title compound, C(17)H(14)O(4), has a shallow envelope conformation, and each of the two outer rings is inclined at an angle of 17.41 (3) degrees. In the solid state, the molecules exist as centrosymmetrically related O-H.O hydrogen-bonded dimers. Two intramolecular O-H.O hydrogen bonds, involving the central carbonyl O atom and having a graph-set motif of S(6), are observed. These intramolecular interactions lead co-operatively to an O-H.O.H-O pattern that has a binary graph-set motif of R(2)(1)(10).