共查询到20条相似文献,搜索用时 15 毫秒
1.
Juan Zinczuk Edmundo A. Ruveda Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(6):o408-o410
The title diketo acid, (−)‐,3a,7‐trimethyl‐5,8‐dioxo‐1,4‐ethanoperhydropentalene‐1‐acetic acid, CHO, is shown to aggregate in the solid state as acid‐to‐acid hydrogen‐bonded catemers, whose chains follow 2 screw axes from each carboxyl H atom to the C=O group of a neighboring carboxyl group [O⋯O = 2.672 (4) Å and O⋯H—O = 173°]. Two parallel counterdirectional screw‐related single‐strand hydrogen‐bonded chains pass through the cell in the a direction. Two intermolecular C=O⋯H—C close contacts are present in this compound. Both this diketo acid and its enol lactone, (+)‐parasantonide [systematic name: (−)‐,3a,7‐trimethyl‐5‐oxo‐1,4‐ethenoperhydropentalene‐1,8‐carbolactone], CHO, have an R configuration at the methylated chiral center adjacent to the carboxyl group, unlike the precursor from which they are derived, viz. (−)‐santonic acid. 相似文献
2.
Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(1):o22-o23
The title keto acid, (+)‐23,24‐dinor‐3‐oxochol‐4‐en‐22‐oic acid, C22H32O3, forms carboxyl‐to‐ketone hydrogen‐bonding catemers [O?O = 2.699 (4) Å and O—H?O = 173°], linking molecules screw‐related in b. The four molecules in the cell form two parallel counter‐directional chains, screw‐related in a. Intermolecular C—H?O=C close contacts to different neighboring molecules were found for the ketone and the acid. 相似文献
3.
Roger A. Lalancette Andrew P. J. Brunskill Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):1260-1262
Molecules of the title compound, C9H14O3, adopt a chiral `boat–chair' conformation, in which the carboxyl group avoids potential cross‐ring ketone interactions by an outward `equatorial' orientation. The asymmetric unit contains two such molecules, one conformationally fixed without disorder, (I), and the other, (I′), extensively disordered, both in the bond lengths and angles of the carboxyl and by a coupled `up‐down' conformational disordering [ratio of 60:40 (1)] of the remote ends of the boat–chair system. Each molecule in the asymmetric unit forms a centrosymmetric hydrogen‐bonded carboxyl dimer with a second molecule of its own type. For (I), O?O = 2.658 (3) Å and O—H?O = 174°. For (I′), O?O = 2.653 (3) Å and O—H?O = 165°. A number of intermolecular C=O?H—C close contacts are found. 相似文献
4.
Hugh W. Thompson Marie L. Cot Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):o727-o729
The title compound, (1R)‐4,7,7‐trimethyl‐3‐oxobicyclo[2.2.1]heptane‐2‐endo‐acetic acid, C12H18O3, like its lower homolog, forms carboxyl‐to‐ketone hydrogen‐bonding catemers (Z′ = 2) [O⋯O = 2.729 (5) and 2.707 (5) Å, and O—H⋯O = 165 and 170°] with screw‐related components. The two molecules of the asymmetric unit differ slightly in conformation and produce two counter‐aligned hydrogen‐bonding chains, both aligned with the b axis. Close intermolecular C—H⋯O=C contacts exist for the ketone group of one molecule and for both the ketone and carboxyl functions in the other. 相似文献
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Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):841-843
In the the title compound, 1,7‐dimethyl‐8‐oxo‐4bα,7α‐gibba‐1,3,4a(10a)‐triene‐10β‐carboxylic acid monohydrate, C18H20O3·H2O, the water of hydration accepts a hydrogen bond from the carboxyl and donates hydrogen bonds to the carboxyl carbonyl and the ketone in two different screw‐related neighbors, which are mutually translational, yielding a complex three‐dimensional hydrogen‐bonding array. 相似文献
7.
Elizabeth M. Kikolski Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(7):o394-o396
The asymmetric unit of the title compound, C24H36O4, contains three molecules, all differing in their side‐chain conformations and all linked by hydrogen bonding confined entirely within a three‐molecule block. One connection is of the acid‐to‐ketone type [O⋯O = 2.7055 (19) Å and O—H⋯O = 180°] and the other involves carboxyl pairing [O⋯O = 2.6485 (18) and 2.6598 (18) Å, and O—H⋯O = 168 and 174°]. Numerous intermolecular C—H⋯O close contacts connect neighbouring molecules. 相似文献
8.
Mark Davison Elizabeth M. Kikolski David Mostafavi Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(4):o249-o252
The (+)‐(αS,1S,4R)‐diastereomer of the title structure, C10H16O3, aggregates in the solid as non‐symmetric dimers with disorder in both carboxyl groups [O·O = 2.710 (5) and 2.638 (5) Å]. The two molecules constituting the asymmetric unit pair around a pseudo‐twofold rotational axis and differ only slightly in their distances and angles, but one methyl group displays rotational disorder absent in the other molecule. Five intermolecular C—H·O close contacts exist, involving both ketone groups. The (+)‐(αR,1R,4R)‐diastereomer exists in the crystal in its closed‐ring lactol form, (3R,3aR,6R,7aR)‐2,3,3a,4,5,6,7,7a‐octahydro‐7a‐hydroxy‐3,6‐dimethylbenzo[b]furan‐2‐one, C10H16O3, and aggregates as hydrogen‐bonded catemers that extend from the hydroxyl group of one molecule to the carbonyl group of a neighbor screw‐related along b [O·O = 2.830 (3) Å and O—H·O = 169°]. One close intermolecular C—H·O contact exists involving the carbonyl group. 相似文献
9.
Jacob M. Newman Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):o402-o404
The title keto acid, C20H26O4, forms carboxyl‐to‐ketone hydrogen‐bonding catemers [O?O = 2.653 (5) Å and O—H?O = 172 (5)°], linking translationally related molecules via the A‐ring ketone. The two molecules in the cell form two parallel counter‐directional chains, screw‐related in b. A total of four intermolecular C—H?O=C close contacts was found, involving both ketone functions. 相似文献
10.
Alan Barcon Andrew P. J. Brunskill Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):o140-o142
The title monohydrate, C7H10O3·H2O, aggregates as a complex hydrogen‐bonding network, in which the water molecule accepts a hydrogen bond from the carboxyl group of one molecule and donates hydrogen bonds to ketone and carboxyl Czdbnd;O functions in two additional molecules, yielding a sheet‐like structure of parallel ribbons. The keto acid adopts a chiral conformation through rotation of the carboxyl group by 62.50 (15)° relative to the plane defined by its point of attachment and the ketone C and O atoms. Two C—H⋯O close contacts exist in the structure. 相似文献
11.
Roger A. Lalancette Andrew P. J. Brunskill Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o491-o493
In the title compound, C12H16O3·H2O, the water of hydration accepts a hydrogen bond from the carboxyl group and donates hydrogen bonds to the carboxyl carbonyl and the ketone groups of two different neighbors, yielding a complex three‐dimensional hydrogen‐bonding array. There are two independent hydrated molecules in the asymmetric unit (Z′ = 2) related by a pseudo‐translation. 相似文献
12.
Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(10):o580-o582
In the title compound, C15H24O3, derived from a naturally occurring sesquiterpenoid, the asymmetric unit consists of two molecules differing by 167.4 (8)° in the rotational conformation of the carboxyl group. Each molecule aggregates separately with its own type as carboxyl‐to‐ketone hydrogen‐bonding catemers [O⋯O = 2.715 (6) and 2.772 (6) Å, and O—H⋯O = 169 and 168°]. This generates two crystallographically independent single‐strand hydrogen‐bonding helices passing through the cell in the b direction, with opposite end‐to‐end orientations. One intermolecular C—H⋯O=C close contact exists for the carboxyl group of one of the molecules. The structure is isostructural with that of a closely related unsaturated keto acid reported previously. 相似文献
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Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(5):o274-o276
The title keto acid crystallizes as a solvate, C21H25FO4·C2H4O2, with two molecules each of steroid and acetic acid per asymmetric unit. The former are approximately parallel, with opposite end‐to‐end orientation, and form translational carboxyl‐to‐ketone hydrogen‐bonding catemers [O⋯O = 2.679 (6) and 2.650 (5) Å, and O—H⋯O = 165 and 162°] that involve the 3‐ketone group and follow the a axis. The acetic acid molecules are paired by hydrogen bonding, and neither they nor the F atom nor the 11‐ketone group play any overt role in the hydrogen‐bonding scheme of the steroid. Intermolecular C—H⋯O=C close contacts involving three different neighboring molecules exist to the 11‐ketone group, the steroidal carboxyl group and one of the acetic acid molecules. 相似文献
15.
L. C. R. Andrade J. A. Paixo M. J. M. De Almeida F. M. Fernandes Roleira E. J. Tavares da Silva 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(3):o131-o133
The title compounds, both C23H34O5, are the 5α and 5β configurations of two diacetate epimers. The 5β‐diacetate crystallizes in an hexagonal structure, unusual for steroid molecules. The unit cell has an accessible solvent volume of 358 Å3, responsible for clathrate behaviour. The 5β‐epimer also features some shorter than average bond lengths in the 3α,4β‐acetoxy groups. The conformations of the molecules of both epimers are compared with those obtained through abinitio quantum chemistry calculations. Cohesion of the crystals can be attributed to van der Waals and weak molecular C—H⋯O interactions. 相似文献
16.
Andrew P. J. Brunskill Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1075-1078
The anhydrous form, (I), of the title compound, (?)‐2‐(1,2,3,4,4a,7‐hexahydro‐4a,8‐dimethyl‐1,7‐dioxo‐2‐naphthyl)propionic acid, C15H18O4, derived from a naturally occurring sesquiterpenoid, has two molecules in the asymmetric unit, (I) and (I′), differing in the conformations of the saturated ring and the carboxyl group. The compound aggregates as carboxyl‐to‐ketone hydrogen‐bonding catemers [O?O = 2.776 (3) and 2.775 (3) Å]. Two crystallographically independent sets of single‐strand hydrogen‐bonding helices with opposite end‐to‐end orientation pass through the cell in the b direction, one consisting exclusively of molecules of (I) and the other entirely of (I′). Three C—H?O=C close contacts are found in (I). The monohydrate, C15H18O4·H2O, (II), with two molecules of (I) plus two water molecules in its asymmetric unit, forms a complex three‐dimensional hydrogen‐bonding network including acid‐to‐water, water‐to‐acid, water‐to‐ketone, water‐to‐water and acid‐to‐acid hydrogen bonds, plus three C—H?O=C close contacts. In both (I) and (II), only the ketone remote from the acid is involved in hydrogen bonding. 相似文献
17.
J. I. F. Paixo J. A. R. Salvador J. A. Paixo A. Matos Beja M. Ramos Silva A. M. d'A. Rocha Gonsalves 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o72-o74
In the title compound, C21H30O3, a potential inhibitor of aromatase, all rings are fused trans. Rings A and C have chair conformations which are slightly flattened, whereas the conformation of ring B is close to a half‐chair. Ring D has a 14α‐envelope conformation. The steroid nucleus has a small twist, as shown by the C19—C10⋯C13—C18 (steroid numbering) torsion angle of −6.9 (3)°. Ab initio calculations of the equilibrium geometry of the molecule reproduce this small twist, which appears to be due to the conformation of ring B rather than to packing effects. 相似文献
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Jacob M. Newman Markos M. Papadakis Hugh W. Thompson Roger A. Lalancette 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):m89-m91
The title compound, [Fe(C6H5O2)(C7H7O)], adopts a conformation involving partial staggering of its rings and aggregates in the solid as acid‐to‐ketone hydrogen‐bonding dimers [O?O = 2.720 (4) Å and O—H?O = 164°] having centrosymmetrically related components. Close intermolecular C—H?O contacts were found to both carboxyl O atoms. 相似文献
20.
Mark Davison Elizabeth M. Kikolski Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(6):o449-o451
In the title compound, C10H16O3, the two molecules of the asymmetric unit form acid‐to‐ketone hydrogen‐bonded chains. The two species differ only very slightly and are related by a pseudo‐center, so that the apparent translational relationship among the units of the hydrogen‐bonded chain is actually a pseudo‐translation, with the molecules alternating in type. Two counterdirectional pairs of chains proceed through each cell [O⋯O = 2.743 (2) and 2.683 (2) Å, and O—H⋯O = 171 (3) and 157 (3)°]. Three intermolecular C—H⋯O close contacts were found, involving all three O atoms of one of the molecules. 相似文献