2-Ferrocenyl-2-[(2-ferrocenylethen-yl)(morpholin-4-yl)meth-yl]-1,3-di-thiol-ane

The mol-ecular structure of 2-ferrocenyl-2-[(2-ferrocenylethen-yl)(morpholin-4-yl)meth-yl]-1,3-di-thiol-ane, [Fe2(C5H5)2(C19H21NOS2)] or C29H31Fe2NOS2, has the ferrocenyl fragments in a trans disposition with respect to the vinyl group. One of the methyl-ene groups is disordered over two sites with occupancies of 0.782 (13):0.218 (13). In the crystal, cyclo-penta-dienyl-C-H⋯O(morpholin-yl) inter-actions feature within helical chains parallel to the c-axis direction. The chains are connected by methyl-ene- and cyclo-penta-dienyl-C-H⋯O(cyclo-penta-dien-yl) inter-actions.

Hypervalent-iodine induced quasi-Favorskii C-ring contraction of 12-oxosteroids: a shortcut to C-norsteroids

Treatment of 12-oxosteroids with PhI(OAc)(2) and KOH in refluxing methanol triggers a quasi-Favorskii C-ring contraction leading to the corresponding 11α-alcoxycarbonyl-C-norsteroids in moderate yields. This constitutes the first one-step synthetic alternative to C-norsteroids starting from 12-oxosteroids.

Tunable recognition of the steroid alpha-face by adjacent pi-electron density

We report a previously unknown recognition motif between the alpha-face of the steroid hydrocarbon backbone and pi-electron-rich aromatic substrates. Our study is based on a systematic and comparative analysis of the solid-state complexation of four steroids with 24 aromatic molecules. By using the solid state as a medium for complexation, we circumvent solubility and solvent competition problems that are inherent to the liquid phase. Characterization is performed using powder and single crystal X-ray diffraction, infrared solid-state spectroscopy and is complemented by a comprehensive cocrystal structure prediction methodology that surpasses earlier computational approaches in terms of realism and complexity. Our combined experimental and theoretical approach reveals that the alpha...pi stacking is of electrostatic origin and is highly dependent on the steroid backbone's unsaturated and conjugated character. We demonstrate that the alpha...pi stacking interaction can drive the assembly of molecules, in particular progesterone, into solid-state complexes without the need for additional strong interactions. It results in a marked difference in the solid-state complexation propensities of different steroids with aromatic molecules, suggesting a strong dependence of the steroid-binding affinity and even physicochemical properties on the steroid's A-ring structure. Hence, the hydrocarbon part of the steroid is a potentially important variable in structure-activity relationships for establishing the binding and signaling properties of steroids, and in the manufacture of pharmaceutical cocrystals.

Beckmann reactions of steroidal spirocyclic oximes derived from the 16beta,23:23,26-diepoxy-22-oxo moiety

The Beckmann rearrangement of the syn and anti isomers of the spirocyclic oxime derived from a 16beta,23:23,26-diepoxy-5beta-cholestan-22-one was studied. Whereas the anti isomer always follows the Beckmann fragmentation course, the syn isomer, depending on the reaction conditions, follows the normal Beckmann rearrangement course and/or the isomerization to the anti isomer followed by the fragmentation course.

Synthesis and antiproliferative activity of A-ring aromatised and conduritol-like steroidal compounds

A simple approach to aromatization of steroidal quinols and epoxyquinols using a catalytic amount of TMSOTf is reported. Beside acetylation of the angular OH, the acid-catalyzed (TfOH) dienone-phenol rearrangement occurred affording "para" products, or in the case of blocked position 4, the acetoxy group 1,2-migration leads to the formation of "meta" products. Using epoxyquinol derivative as a substrate, the acetoxy group elimination was observed, followed by acid-catalyzed epoxy-ring opening and subsequent double bond migration, giving as a final product Delta(9,11)A-ring aromatized compounds. Synthesis of conduritol-like compounds and structure confirmation by X-ray crystallography of the precursor of steroidal conduritol is also described. In addition, the results of extensive antiproliferative screening against a panel of 60 cancer cell lines are presented.

Crystal structure of 4,6-O-ethylidene-N-(2-hydroxybenzylidene)-beta-D-glucopyranosylamine

4,6-O-Ethylidene-N-(2-hydroxybenzylidene)-beta-D-glucopyranosylamine was synthesized and characterized using analytical, spectral and single-crystal X-ray diffraction methods. The anomeric nature of the saccharide moiety was proposed based on 1H NMR studies and was confirmed by the crystal structure. The lattice structure of this compound was compared with that of its analogues.

The saccharide-hydrazide linkage: molecular and crystal structures of the semicarbazide derivatives of D-glucose, D-galactose, and D-xylose, including a 'forbidden' conformation of the galactose derivative

The X-ray crystal structures of the semicarbazide derivatives of D-glucose, D-galactose, and D-xylose are described. All are glycopyranosyl derivatives in the solid state. The glucose semicarbazide crystallizes as a dihydrate. Two different conformations of the galactose semicarbazide are found, one having the gg side-chain orientation unfavorable for monosaccharides having the 4C(1)-D-galacto configuration. In the two other known examples, this conformation is stabilized by an intramolecular hydrogen bond, but in the current structure, the hydrogen bonds involving the side chain are intermolecular. In these semicarbazides the N [bond] N [bond] C[double bond] O torsional angle is approximately 180 degrees, in contrast to the angles of 0.60 and 13.9 degrees in the two solid-state conformations of 2-benzoyl-1-(alpha-D-xylopyranosyl)hydrazine [Ernholt, B. V.; Thomsen, I. B.; Lohse, A.; Plesner, I. W.; Jensen, K. B.; Hazell, R. G.; Liang, X.; Jakobsen, A.; Bols, M. Chem. Eur. J. 2000, 6, 278-287]. The water molecules and the carbonyl oxygen are heavily involved in H-bonding.

Synthesis, characterization and the first crystal structure of the Zn(II) complex of 4,6-O-ethylidine-N-(2-hydroxybenzylidene)-beta-D-glucopyranosylamine

4,6-O-Ethylidine-N-(2-hydroxybenzylidene)-beta-D-glucopyranosylamine (H(3)L(1)) and N-(5-bromo-2-hydroxybenzylidene-4,6-O-ethylidine-beta-D-glucopyranosylamine (H(3)L(2)) molecules possessing a single bond C-1 single bond N double bond C(H) single bond moiety for metal-ion binding were synthesized by condensing the 4,6-O-ethylidene-beta-D-glucopyranosylamine with salicylaldehyde or 5-bromosalicylaldehyde. Complexes of these ligands with Zn(II) were isolated and characterized using elemental analysis, FTIR, UV-Vis absorption, NMR spectroscopic and FAB mass spectrometric techniques. The structure of the Zn(II) complex derived from H(3)L(1) was established for the first time by a single-crystal X-ray diffraction study. The anomeric nature of the saccharide moiety was established based on (1)H NMR studies and was confirmed by the crystal structure. Further, the structure and binding aspects of the ligand, and the coordination features of this in its Zn(II) complex were derived from the corresponding crystal structure.

Synthesis, characterisation and crystal structures of Schiff bases from the reaction of 4,6-O-ethylidene-beta-D-glucopyranosylamine with substituted salicylaldehydes

Multiple chemical modifications were carried out on D-glucose to result in the corresponding Schiff bases. Such modifications performed on D-glucose not only helped in increasing the solubility of the products in nonaqueous solvents, but also restricted the anomerisation of the saccharide moiety in solution. NMR study of the products revealed the presence of the beta-anomeric form of the saccharide moiety in Me(2)SO solution. All the compounds were characterised by analytical and spectral methods. The literature is devoid of any crystal structures of saccharide-Schiff base combinations of the type reported in this paper. The crystal structures of these molecules exhibited a tridentate, ONO binding core. These studies further revealed that the compounds in the solid state were in the beta-D-pyranose form with the (4)C(1) chair conformation. The compounds exhibited interesting lattice structures assisted through weak interactions of the type O-H...O and C-H...O. The lattice structure of one of these compounds exhibited channels filled with chloroform molecules.

Molecular and crystal structures of N-aryl-beta-D-glycopyranosylamines from mannose and galactose

The molecular and crystal structures of 12 N-aryl-beta-D-glycopyranosylamines have been determined by X-ray crystallography. Six of these are mannose derivatives, the N-p-bromophenyl (1), N-p-tolyl (2), N-m-chlorophenyl (3), N-p-methoxyphenyl (4), N-o-chlorophenyl (5), and N-o-tolyl (6) derivatives that are formed by reaction with the corresponding substituted anilines. The remaining six are galactose derivatives, the N-phenyl (7), N-p-chlorophenyl (8), N-p-bromophenyl (9), N-p-iodophenyl (10), N-p-nitrophenyl (11) and N-p-tolyl (12), derivatives prepared similarly. Compounds 1-3 assume the same packing arrangement. Compounds 4, 5, and 6 assume unique packing arrangements, although that assumed by 4 is closely related to that assumed by 1-3. Compounds 7-11 assume the same packing arrangement; that assumed by 12 is closely related to that assumed by 7-11. That the same packing arrangements can be maintained in spite of substantial changes in the electronic and steric nature of the substituent on the aryl ring reflects the strength of the hydrogen bond network connecting the monosaccharide portions of the molecules in the solid state. A hydrogen bonding motif found in all six mannose structures is a mutual interaction between translationally related molecules involving O-3-H...O-5 and O-6-H...O-4 hydrogen bonds. The recurrence of this motif throughout this group of mannosylamines suggests that it is an especially favorable interaction that might be expected to occur also in related macromolecular systems.

Molecular and crystal structures of N-arylglycopyranosylamines formed by reaction between sulfanilamide and D-ribose, D-arabinose and D-mannose

The X-ray crystal structures of three monosaccharide derivatives prepared by the reaction of sulfanilamide with D-ribose, D-arabinose, and D-mannose have been determined. The derivatives are N-(p-sulfamoylphenyl)-alpha-D-ribopyranosylamine (1), N-(p-sulfamoylphenyl)-alpha-D-arabinopyranosylamine (2), and N-(p-sulfamoylphenyl)-beta-D-mannopyranosylamine monohydrate (3). The monosaccharide ring of 1 and 2 has the 1C4 conformation, stabilized in 1 by an intramolecular hydrogen bond from 0-2 to 0-4. Compound 3 has the 4C1 conformation at the monosaccharide ring and the gt conformation at the C-6-O-6 side chain. Occupancy of the water molecule in the crystal of 3 actually examined was 22%. The degree of interaction between sulfamoyl groups and monosaccharide moieties varies from structure to structure. The packing arrangement of 2 involves hydrogen bonding between sulfamoyl groups and monosaccharide hydroxyl groups, but interactions of this type are fewer in 1, and in 3 the hydrogen bonds are either strictly between monosaccharide hydroxyl groups or strictly between sulfamoyl groups. Pairs of hydrogen bonds (two-point contacts) link neighboring molecules in all three structures, between screw-axially related molecules in 1 and 2 and between translationally related molecules in 3. The contact in 3 defined by the O-3-H...O-5 and O-6-H...O-4 hydrogen bonds is found in several other N-aryl-beta-D-mannopyranosylamine crystal structures and is apparently an especially favorable mode of intermolecular interaction in these compounds.

Schiff bases or glycosylamines: crystal and molecular structures of four derivatives of D-mannose

Crystal and molecular structures of four derivatives of D-mannose are described. Each could exist as either an open-chain Schiff base or as a glycosylamine in the solid state. The derivative formed upon reaction of D-mannose with hydroxylamine is an open-chain oxime, but those formed upon reaction with semicarbazide, aniline, and p-chloroaniline are glycosylamines. The oxime, which crystallizes as the syn-(E) isomer, has a fully extended carbon chain. The glycosylamines are all beta-pyranoses. The packing arrangement of the oxime involves 'head-to-tail' hydrogen bonding. The semicarbazide derivative, which crystallizes as a dihydrate, features a hydrogen-bonded intramolecular bridge formed by the two water molecules and linking O-6 to the carbonyl oxygen atom. The packing arrangements of the aniline and p-chloroaniline derivatives differ from each other but are nevertheless closely related by similar hydrogen-bonding interactions.

A comparative structural study of the steroid epimers: 17 beta-amino-1,3,5(10)-estratrien-3-ol, 17 alpha-amino-1,3,5(10)-estratrien-3-ol, and some derivatives by 1H NMR, and x-ray diffraction analysis

The epimers 17 beta-amino-1,3,5(10)-estratrien-3-ol and 17 alpha-amino-1,3,5(10)-estratrien-3-ol were synthesized. 17 beta-Amino-1,3,5(10)-estratrien-3-ol was prepared by catalytic hydrogenation of the estrone-oxime. The 17 alpha-amino epimer was obtained from estradiol, via tosylate, followed by nucleophilic displacement by sodium azide and subsequent reduction with LiAlH4. They were characterized by spectroscopic methods. Determination of the crystal structures of 3-(toluene-4-sulfonyloxy)-17 alpha-1,3,5(10)-estratriene, 3-(toluene-4-sulfonyloxy)-17-alpha-amino,1,3,5(10)-estratriene hydrochloride, 17 beta-acetylamino-1,3,5(10)-estratriene-3-ol, and 3-acetoxy-17 beta-acetylamino-1,3,5(10)-estratriene enabled us to characterize the structure of the 17 alpha and 17 beta amino epimers for the first time.

The estradiol pharmacophore: ligand structure-estrogen receptor binding affinity relationships and a model for the receptor binding site

The accumulated knowledge on the binding of estradiol (E2) and its analogs and the results of affinity-labeling studies have been reviewed and are used herein to derive a binding site model for the estrogen receptor (ER). Estradiol is nonpolar and hydrophobic, except at its molecular termini. Most of its skeletal flexibility resides in the B-ring, and it probably binds in a low-energy conformation. The phenolic OH group in the A-ring contributes about 1.9 kcal/mol to the binding free energy and probably acts primarily as a hydrogen bond donor. The 17 beta-hydroxyl group in the D-ring contributes approximately 0.6 kcal/mol to the binding and probably acts as a hydrogen bond acceptor, either directly or via a water molecule. There also seems to be a degree of flexibility in the region of the receptor that encompasses the D-ring. The aromatic ring contributes about 1.5 kcal/mol, probably through weak polar interactions with receptor residues that contact the beta-face of the steroid. The receptor seems to surround the ligand, so that all four rings contribute significantly to binding. Small hydrophobic substituents enhance binding affinity at positions 4, 12 beta, 14, and 16 alpha; whereas, larger hydrophobic substituents are tolerated at positions 7 alpha, 11 beta, and 17 alpha. In general, the ER is intolerant of polar substituents. Based on E2 analogs bearing affinity-labeling groups, cysteine residues might be present in the binding site in the area of C-4, C-17 alpha, and C-17 beta, and a lysine residue might be located near C-16. Models that represent the limits of deformability of the ligand binding site, the position of preformed pockets, and space occupied by the receptor are presented. The various elements in this model for the binding of steroidal estrogens by the estrogen receptor are consistent with evidence emerging from the crystal structures of related nuclear hormone receptor ligand complexes.

Crystal and molecular structure of noscapine 1

Noscapine, C22H24NO7 · HCl, has been elucidated as (S)-6,7-dimethoxy-3-(5,6,7,8-tetrahydro-4-methoxy-6-methyl-1,3-dioxolo[4,5-g]isoquinolin-5-ly)-1 (3H)-isobenzofuranone, orthorhombic, P212121, a = 8.584(1) Å, b = 22.318(2) Å, c = 25.062(1) Å, Z = 8, Dx = 1.245 mgm−3, μ = 1.75 mm−1, F(000) = 1804.0, Mw = 450.88, R = 0.070 and Rw = 0.073. The molecule consists of one isoquinoline ring with an endocyclic substituent. There are two molecules in the asymmetric unit and they are similar in their conformations except the conformation of the methoxy group at the isobenzofuranone moiety. In both molecules the dioxolo ring and the oxolo ring are in the envelop conformation and the heterocyclic rings of isoquinolines are in half-chair conformation. The methoxy groups attached to the benzene ring of the isoquinoline are rotated from the mean plane by − 29(2)° and −16(2)° in the two molecules. The angle between the heterocyclic and oxolo rings in the two molecules are 48.6(4)° and 42.6(3)°, respectively. The structure is stabilized by van-der-Waals interactions.

X-ray and conformational investigation of 6-deoxy-6-C-(1,5-di-O-acetyl-2,3-O- isopropylidene-beta-D-allo-pentofuranos-5-yl)-1,2:3,4-di-O-isopro pylidene-alpha-D-galactopyranose and 6-C-(benzyl 5-deoxy-2,3-O-isopropylidene-beta-D- ribofuranosid-5-yl)-1,2:3,4-di-O-isopropylidene-D-glycero-alpha-D-galac to-hexopyranose

The structures of the title compounds (2b and 3) have been investigated in the solid state by X-ray methods. The crystals of 2b are monoclinic, space group P2(1), and of 3 orthorhombic, space group P2(1)2(1)2(1). The cell dimensions are: for 2b, a = 9.910(2), b = 11.745(1), c = 11.810(3) A, beta = 97.32(1) degrees; and for 3, a = 6.103(1), b = 15.954(1), c = 28.855(3) A. Both structures were solved by direct methods, and refined by a full-matrix, least-squares procedure giving for 2b, R = 0.0541 (unit weight), and for 3, R = 0.0451 (RW = 0.0445). The galactopyranose rings of 2b and 3 adopted a twist and a mixed twist-screw conformation, respectively. The absolute configuration at C-7 in 2b, as well as at C-6 in 3, was determined to be (R). Relatively strong intermolecular hydrogen bonds were observed in the crystal structure of 3.

Synthesis, conformational analysis, and the glycosidic coupling reaction of substituted 2,7-dioxabicyclo[4.1.0]heptanes: 1,2-anhydro-3,4-di-O-benzyl-beta-L- and beta-D-rhamnopyranoses

1,2-Anhydro-3,4-di-O-benzyl-alpha-L-rhamnopyranose was synthesized from L-rhamnose, while the D-enantiomer was synthesized from methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-mannopyranoside. For both of the syntheses, the key intermediates were 2-O-acetyl-3,4-di-O-benzyl-alpha-D- and -alpha-L-rhamnopyranosyl chlorides that were quantitatively prepared from the corresponding diacetates by chlorination. Ring closure of the chlorides was carried out readily with potassium tert-butoxide in oxolane, and crystalline 1,2-anhydro-3,4-di-O-benzyl-beta-D- and beta-L-rhamnopyranose were obtained in high yields. Conformational calculations, which were carried out using vicinal proton-proton coupling constants by the modified Karplus equation, suggested that the conformations of the pyranose rings of the title compounds were basically a half chair (4H5) with some flattening at C-4. Force-field calculations (MMP2) confirmed the experimental conformation with good agreement. The coupling reaction of the 1,2-anhydro-L-rhamnose ether with 1,2;3,4-di-O-isopropylidene-alpha-D-galactopyranose was effected in oxolane by catalysis by a Lewis acid, and only the alpha-linked disaccharide was obtained.