Biomedical subjects
Publications and source records attributed to Anthony Linden.
In both of the title compounds, C(23)H(19)ClN(2)O, (I), and C(23)H(18)Cl(2)N(2)O, (II), the molecular packing is influenced by weak intermolecular C-H.O and C-H.pi interactions, but despite the chemical similarity of the compounds, the packing in (II) is entirely different from that observed in (I).
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.
The title compounds, 4-(2-naphthyloxymethylcarbonyl)morpholine, C(16)H(17)NO(3), (I), and 4-methyl-1-(2-naphthyloxymethylcarbonyl)piperazine, C(17)H(20)N(2)O(2), (II), are potential antiamnesics. The morpholine ring in (I) and the piperazine ring in (II) adopt chair conformations. In (I), the molecules are linked by weak intermolecular C-H.O interactions into chains that have a graph-set motif of C(10), while in (II), the molecules are linked by weak intermolecular C-H.O interactions that generate two C(7) graph-set motifs. The dihedral angle between the naphthalene moiety and the best plane through the morpholine ring is 20.62 (4) degrees in (I), while the naphthalene moiety is oriented nearly perpendicular to the mean plane of the piperazine ring in (II).
The title compounds 1-(2-naphthyloxymethylcarbonyl)piperidine, C(17)H(19)NO(2), (I), and 3-methyl-1-(2-naphthyloxymethylcarbonyl)piperidine, C(18)H(21)NO(2), (II), are potential antiamnesics. In (II), the methyl-substituted piperidine ring is disordered over two conformations. The piperidine ring has a chair conformation in both compounds. In (I), the molecules are linked by weak intermolecular C-H.O interactions to give networks represented by C(4), C(6) and R(4)(4)(18) graph-set motifs, while in (II), weak intermolecular C-H.O interactions generate R(1)(2)(5), C(4) and C(7) graph-set motifs. The dihedral angle between the naphthalene moiety and the piperidine ring is 33.83 (7) degrees in (I), while it is 31.78 (11) and 19.38 (19) degrees for the major and minor conformations, respectively, in (II).
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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).
The title compounds, namely dimethyl (2RS)-2,3-diphenyl-1,3-thiazolidine-5-spiro-2'-adamantane-4,4-dicarboxylate methanol solvate, C(28)H(31)NO(4)S.0.275CH(4)O, and dimethyl (4RS)-3,4-diphenyl-1,3-thiazolidine-5-spiro-9'-(9'H-fluorene)-2,2-dicarboxylate, C(31)H(25)NO(4)S, were obtained from dipolar [2+3]-cycloadditions of an azomethine ylide with adamantanethione and thiofluorenone, respectively. The structures show that the choice of thioketone affects the regioselectivity of the cycloaddition. The asymmetric unit of the former structure contains two molecules of the thiazolidine derivative plus a site for a partial occupancy (55%) methanol molecule. O-H...O and C-H...O interactions link two of each of these entities into closed centrosymmetric hexamers. The five-membered ring in each structure has an envelope conformation.
The title compound, [Fe(C(5)H(5))(C(21)H(21)O(3))], was obtained from successive Stobbe condensations between ketones and dimethyl succinate. The succinic anhydride five-membered ring is distorted significantly from planarity, with the butadiene moiety being twisted by 49.3 (2) degrees from planarity and the C atoms at the succinic anhydride end of the alkene bonds showing significant pyramidalization. The cyclopentadiene rings of the ferrocenyl moiety adopt an almost eclipsed conformation.
The objective of this study was to synthesise new condensed 1,4-dihydropyridine derivatives and investigate their calcium channel blocking activity. In addition, the in vitro hepatic microsomal bio-transformation of one hexahydroquinoline derivative was studied, 2,6,6-Trimethyl-3-carbmethoxy (carbethoxy)-4-aryl-5-oxo-1,4,5,6,7,8-hexahydroquinoline derivatives were synthesised bymodified Hantzsch synthesis. 1,3,4,5,6,7,8,9-octahydro-7,7-dimethyl-9-arylfuro [3,4-b]quinoline-1,8-dione derivatives were synthesised the reaction of hexahydroquinoline derivatives with pyridinium bromide perbromide. The calcium antagonistic activities of the compounds were determined by tests performed on isolated rat ileum and lamb carotid artery. In vitro hepatic biotransformation of one compound was studied in rat microsomes. Although compounds 3, 18 and 28 showed promising relaxant activity, they were less active than nicardipine (CAS 55985-32-5) in isolated rat ileum. In all studied concentrations, compounds 5 and 20 were more active than nicardipine in lamb carotid artery. These compounds showed high tissue selectivity compared with nicardipine. In addition, in vitro hepatic microsomal biotransformation of compound 2 produced its lactone derivative (compound 34). This metabolite was verified by HPLC. In the hexahydroquinoline series, the compounds having ortho substituted phenyl substituent were more active than the meta isomers. Lactone derivatives were found less active than hexahydroquinoline derivatives in respect to calcium antagonistic activity.
3-O-Mesyl-1,6-di-O-trityl-beta-D-fructofuranosyl-(2-->1)-6-O-trityl-alpha-D-glucopyranoside (3) was synthesized via stannylation of 6,1',6'-tri-O-tritylsucrose with dibutyltin oxide in benzene, followed by treatment of the crude product with methanesulfonyl chloride in the presence of triethylamine in dichloromethane at 0 degrees C. A similar treatment of the tri-tritylsucrose in toluene, instead of benzene, yielded 4-O-mesyl-1,6-di-O-trityl-beta-D-fructofuranosyl-(2-->1)-6-O-trityl-alpha-D-glucopyranoside (4) as the major product. The X-ray crystal structure of the corresponding acetyl derivative, 3-O-acetyl-4-O-mesyl-1,6-di-O-trityl-beta-D-fructofuranosyl-(2-->1)-2,3,4-tri-O-acetyl-6-O-trityl-alpha-D-glucopyranoside (5), confirms the position and stereochemistry of the methanesulfonyl group at C-4 of the fructofuranosyl ring.
At 160 K, one of the Cl atoms in the furanoid moiety of 3-O-acetyl-1,6-dichloro-1,4,6-trideoxy-beta-D-fructofuranosyl 2,3,6-tri-O-acetyl-4-chloro-4-deoxy-alpha-D-galactopyranoside, C(20)H(27)Cl(3)O(11), is disordered over two orientations, which differ by a rotation of about 107 degrees about the parent C-C bond. The conformation of the core of the molecule is very similar to that of 3-O-acetyl-1,4,6-trichloro-1,4,6-trideoxy-beta-D-tagatofuranosyl 2,3,6-tri-O-acetyl-4-chloro-4-deoxy-alpha-D-galactopyranoside, particularly with regard to the conformation about the glycosidic linkage.
The title compound, C(36)H(49)NO(5).H(2)O, has the outer two six-membered rings of the steroid nucleus in chair conformations. The central ring B of the steroid nucleus is in an 8beta,9alpha-half-chair conformation, while ring D of the steroid adopts a slightly distorted 13beta,14alpha-half-chair conformation. The piperidine ring is in a chair conformation. The methoxybenzylidene moiety has an E configuration with respect to the carbonyl group at position 17. Intermolecular O-H.O and O-H.N hydrogen bonds link the steroid and water molecules into chains which run parallel to the b axis.
At 160 K, the glucopyranosyl ring in 1,6-dichloro-1,6-dideoxy-beta-D-fructofuranosyl 4-chloro-4-deoxy-alpha-D-glucopyranoside monohydrate, C(12)H(19)Cl(3)O(8).H(2)O, has a near ideal (4)C(1) chair conformation, while the fructofuranosyl ring has a (4)T(3) conformation. The conformation of the sugar molecule is quite different to that of sucralose, particularly in the conformation about the glycosidic linkage, which affects the observed pattern of intramolecular hydrogen bonds. A complex series of intermolecular hydrogen bonds links the sugar and water molecules into an infinite three-dimensional framework.
The principle of metal-free activation of enones toward the Diels-Alder reaction with dienes is demonstrated by exploiting the capability of Brønsted acids to activate alpha'-hydroxyenones through hydrogen bonding. The diastereoselective application of such a principle is nicely realized by using a newly designed family of camphor-based chiral enones, which upon catalytic action of either trifluoroacetic or triflic acid lead to the corresponding cycloadducts with high chemical and stereochemical efficiency.
A new type of sugar-amino acid hybrid, which is comprised of a sugar unit (gluco-, galacto-, or mannopyranose) linked through a C-glycosidic linkage to the beta-position of an alpha-unsubstituted beta-amino acid unit, is presented. It is hypothesized that these new compounds, or the oligomeric peptides derived therefrom, might possess the structural features of beta-amino acid oligomers and the chemical and enzymatic resistance of C-glycosides to hydrolysis. The synthetic strategy is based on a new Mannich-type reaction between a chiral acetate enolate equivalent and alpha-amido sulfones derived from the corresponding sugar-C-glycoside aldehydes. While the sugar-C-glycoside aldehyde partner is prepared from well-established transformations on known sugar precursors, the lithium enolate derived from (1R)-endo-2-acetylisoborneol 3 is employed as the key element. This Mannich approach proceeds with essentially perfect diasteromeric control leading to the new beta-amino carbonyl adducts in good yields. Further, cleavage of the camphor auxiliary is smoothly performed by oxidative treatment with ammonium cerium nitrate (CAN). Complementarily, direct peptide-type coupling of the beta-amino carbonyl Mannich adducts with an alpha- or beta-amino acid residue and subsequent CAN-promoted detachment of the auxiliary yields dipeptide fragments bearing a sugar-containing aliphatic side chain and is a process that can be iterated. A preliminary conformational study based on the combination of experimental NMR data and molecular mechanics and molecular dynamics (MD) of one particular adduct is also provided.
The four oligosulfanes, bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)disulfane, C(16)H(24)Cl(2)O(2)S(2), (III), 1,3-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)trisulfane, C(16)H(24)Cl(2)O(2)S(3), (V), 1,4-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)tetrasulfane, C(16)H(24)Cl(2)O(2)S(4), (VII), and 1,6-bis(1-chloro-2,2,4,4-tetramethyl-3-oxocyclobutan-1-yl)hexasulfane, C(16)H(24)Cl(2)O(2)S(6), (VIII), all have similar geometric parameters, with the C-C bond lengths involving the chloro-substituted cyclobutanyl C atom being elongated to about 1.59 A. There are two molecules in the asymmetric units of the tri- and tetrasulfanes, and the molecules in the latter compound have local C(2) symmetry. The molecule of the hexasulfane has crystallographic C(2) symmetry. Most of the cyclobutanyl rings are not perfectly planar and have slight but varying degrees of distortion towards a flattened tetrahedron. The polysulfane chain in each structure has a helical conformation, with each additional S atom in the chain adding approximately one quarter of a turn to the helix.
The As and Tl atoms in title compound, (C(24)H(20)As)[TlI(4)], sit on fourfold inversion centres, resulting in a [TlI(4)](-) anion with D(2d) symmetry and a Tl-I bond length of 2.7691 (3) A. The tetrahedral anion is tetragonally distorted, being flattened in the direction of the c axis of the tetragonal unit cell, so that the two unique I-Tl-I angles differ by about 9 degrees. In contrast, the cation has S(4) symmetry and the tetrahedral coordination geometry of the As atom is very slightly stretched in the direction of the c axis.
The title compound, C(23)H(29)N(3)O(4), has potential calcium modulatory properties. The conformation of the 1,4-dihydropyridine ring is unusual in that it is planar, instead of the usual shallow boat. The 3-nitrophenyl substituent is in the synperiplanar orientation with respect to the dihydropyridine ring plane. The oxocyclohexene ring has a distorted envelope conformation, with the out-of-plane atom being disordered on opposite sides of the ring plane. The molecules are linked into chains by intermolecular hydrogen bonds.