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Biomedical subjects

M Parvez

Publications and source records attributed to M Parvez.

At least 19 recordsLinked to original sources
PubMed2000

Synthesis, resolution, and applications of 2, 2'-bis(diphenylphosphino)-3,3'- binaphtho[2,1-b]furan.

[structure: see text] A short five-step synthesis of (+/-)-2,2'-bis(diphenylphosphino)-3, 3'-binaphtho[2,1-b]furan (BINAPFu, 1) starting from 2-naphthoxyacetic acid is reported. The resolution of BINAPFu 1 was possible using our newly developed resolution procedure for phosphines wherein (1S)-camphorsulfonyl azide was used to prepare the bisphosphinimine of BINAPFu via the Staundinger reaction. BINAPFu consistently outperformed BINAP in an asymmetric Heck reaction between 2,3-dihydrofuran and phenyl triflate.

Journal Article↗
PubMed2000

Mechanistic studies on selectivity in the B(C6F5)3-catalyzed allylstannation of aldehydes: is hypercoordination at boron responsible?

[structure: see text] The selective, B(C6F5)3-catalyzed allylstannation of aldehydes with proximal donor groups is shown to proceed via borane abstraction of the allyl group from the tin reagent and activation of the substrate by "Bu3Sn+". This is supported by a number of 19F NMR experiments. The selectivity of the reaction is not attributable to hypercoordinate boron as proposed by the discoverers of this highly selective reaction but likely involves chelation at tin.

Journal Article↗
PubMed2000

Clemizoledichlorocobalt(II).

The structure of dichloro[1-(p-chlorobenzyl)-2-(1-pyrrolidinylmethyl-N)-1, 3-benzimidazole-N(3)]cobalt(II), [CoCl(2)(C(19)H(20)ClN(3))], contains a molecule of clemizole bound in a bidentate manner to cobalt through its imidazole and pyrrolidinyl N atoms, with significantly different Co-N distances of 1.976 (5) and 2.126 (5) A, respectively. The geometry around cobalt is distorted tetrahedral, with significantly different Co-Cl distances of 2.217 (2) and 2.233 (2) A, and the pyrrolidinyl ring is disordered.

Benzimidazoles↗
PubMed2000

Astemizole tetrachlorocuprate(II).

The structure of ¿3-[(4-fluorophenyl)methyl]-1H-benzimidazol-2-ylidene¿¿1-[2-(4- methox yphenyl)ethyl]-4-piperidin-1-io¿ammonium tetrachlorocuprate(II), (C(28)H(33)FN(4)O)[CuCl(4)], contains diprotonated cations of astemizole hydrogen bonded to three Cl atoms in two different CuCl(4)(2-) anions, with Cl.N distances in the range 3.166 (4)-3.203 (4) A. The geometry around copper is flattened tetrahedral with significantly different Cu-Cl distances which lie in the range 2.1968 (14)-2.2861 (12) A. The phenylethyl C atoms of the (4-methoxyphenyl)ethyl group are disordered indicating the presence of two conformers in the crystals.

Astemizole↗
PubMed1999

Gliclazide.

The crystal structure of gliclazide, N-[(perhydrocyclopenta [c]pyrrol-2-yl)aminocarbonyl]-p-toluenesulfonamide, C15H21B3O3S, a second-generation oral hypoglycemic agent, contains discrete molecules with normal molecular dimensions. Both of the five-membered fused rings adopt envelope conformations. The molecules are linked into chains by intermolecular hydrogen bonds involving amino-H atoms, with N...O separations of 2.967 (3) and 2.949 (3) A.

Crystallography, X-Ray↗
PubMed1999

Coinage Metal Complexes of a Tellurium Diimide: cis-->trans Isomerization and Metal-Metal Interactions.

The different coordination behavior of the ligand tBuN=Te(µ-NtBu)(2)Te=NtBu (L) towards Cu(+) and Ag(+) results from a cis-->trans isomerization. The two Cu(+) ions in [Cu(2)L(3)](2+) (shown schematically) bridge trans and cis isomers of the ligand, whereas the Ag(+) ions in [Ag(2)L(2)](2+) link two trans ligands and exhibit a weak Ag small middle dot small middle dot small middle dotAg interaction.

Journal Article↗
PubMed1997

Antifungal diterpenoid alkaloids from Delphinium denudatum.

The roots of Delphinium denudatum have yielded a new diterpenoid alkaloid, 8-acetylheterophyllisine (1), in addition to the known alkaloids vilmorrianone (2), panicutine (3), denudatine (4), isotalatizidine (5), and condelphine (6), as well as 3-hydroxy-2-methyl-4H-pyran-4-one (7). Compounds 1, 3, and 7 have not been isolated from this plant previously. The structures of compounds 1, 3, and 7 were determined through spectral and X-ray diffraction analyses. Compounds 1-3 have shown antifungal activity against a number of human pathogenic fungi.

Alkaloids↗
PubMed1992

(2S-[2 alpha,3 alpha,3a beta,6 beta(R*),7 alpha, 7a alpha])-6-(3-benzyloxy-2-propyl)-2-hydroxy-2,3,7-trimethylhexahydro-4H- furo [3,2-c]pyran-4-one, a rearrangement product of pyranone derivatives in the tirandamycin A series.

The six- and five-membered heterocyclic rings are cis-fused and adopt twist-boat and half-chair conformations, respectively. The average bond distances are: Csp3-Csp3 1.520 (6), Csp3-Csp2 1.494 (6), C-Cbenz 1.360 (10) and Csp3-O 1.425 (5) A; the C = O and Csp2-O bond lengths are 1.214 (5) and 1.324 (5) A, respectively.

Aminoglycosides↗
PubMed1992

Structure of trans-3,3-dichloro-4-(alpha-chlorobenzyl)-1-methyl-5-phenyl-2-pyrrolidi none.

C18H16Cl3NO, Mr = 368.69, triclinic, P1-, a = 10.360 (1), b = 10.397 (1), c = 10.810 (2) A, alpha = 60.84 (1), beta = 57.22 (1), gamma = 70.97 (1) degrees, V = 852 (1) A3, Z = 2, Dx = 1.437 Mg m-3, Mo K alpha radiation, lambda = 0.71073 A, mu = 0.54 mm-1, F(000) = 380, T = 293 (1) K, R = 0.0287 for 2330 observed reflections with I greater than 3 sigma (I). The five-membered ring has an envelope conformation and the 4-(alpha-chlorobenzyl) and 5-phenyl groups are trans with respect to each other.

Benzyl Compounds↗
PubMed1991

6-Oxo-2,2,4,4,6-pentaphenoxycyclotri-lambda 5-phosphazane-1,3-diene.

C30H26N3O6P3, Mr = 617.48, monoclinic, P2(1)/n, a = 13.200(4), b = 16.714(3), c = 13.438(9) A, beta = 96.38(3) degrees, V = 2946.3 A3, Z = 4, Dx = 1.392 Mg m-3, lambda (Mo K alpha) = 0.71073 A, mu = 0.23 mm-1, F(000) = 1280, T = 293(1) K, R = 0.037 for 4089 observed data with I greater than 3 sigma (I). The P3N3 ring has a boat conformation with a P atom and an N atom 0.396(1) and 0.118(2) A, respectively, out of the plane of the remaining atoms of the ring. One of the P atoms involves a double bond P = O [1.470(1) A] and a P-N single bond [1.683(1) A]. The P-O single bonds and P-N ring bonds range between 1.564(1) and 1.5941) A [mean 1.576(1) A] and 1.546(1) and 1.607(1) A [mean 1.574(1) A], respectively.

Molecular Structure↗
PubMed1991

A simple colorimetric quantification of flavonoids in the flowers of Lonchocarpus cyanescens genus: Lonchocarpus.

As part of a continuing study of the Nigerian flora a chemical analysis of the flavonoids of some plants of the family Papilionaceae prominent in traditional medicine was undertaken. The flowers of the selected plants were extracted and the flavonoids were detected and identified by standard methods. In any such biochemical/chemotaxonomic study where a sizeable number of plants are analysed and in which small differences in type and quantity of each sample are critical, a fast and accurate method of determining the composition becomes paramount. In this work, the determination of the concentration of each flavonoid as a factor of absorbance on a simple single cell photoelectric colorimeter (Seagull Electric Institute Model-1) is reported. The results obtained for Lonchocarpus cyanescens genus Lonchocarpus were consistently satisfactory, sensitive and economical compared with the standard thin layer procedure. As far as the authors know, this is the first report of this method in flavonoid work.

Antiviral Agents↗