Search Results
Nucleoside analogues from push-pull functionalized branched-chain pyranosides
The reaction of methyl 4,6-O-benzylidene-2-deoxy-α-D-erythro- hexopyranosid-3-ulose (1) with ethynylmagnesium bromide in tetrahydrofuran and subsequent trimethylsilylation yielded the methyl 4,6-O-benzylidene-2-deoxy-3-C- ethynyl-3-O-trimethylsilyl-α-D-ribo-hexopyranoside (3). Push-pull functionalization of 3 with N,N,N′,N′,N″,N″- hexamethylguanidinium chloride under basic conditions and following deprotection afforded the spiro{2,5-dihydro-3-dimethylamino-furan-2,8'-4',4'a,6',7',8',8'a- hexahydro-6'-methoxy-2'-phenyl-pyrano[3,2-d][1,3]dioxine}-5- ylidenemalononitrile (9). Furthermore, compound 1 reacted with N,N-dimethylformamide dimethylacetal to furnish methyl (E)-4,6-O-benzylidene-2- deoxy-2-dimethylaminomethylene-α-D-erythro-hexopyranosid-3-ulose (10). Treatment of 10 with methylhydrazine and amidines yielded (4S,5aR,8R,9aS)-2,5a, 6,9a-tetrahydro-4-methoxy-2-methyl-8-phenyl-4H-[1,3]dioxino[4',5':5,6]pyrano[4, 3-c]pyrazole (11a) and (2R,4aR,6S,10bS)-4,4a,6,10b-tetrahydro-6-methoxy-2- phenyl[1,3]dioxino[4',5':5,6]pyrano[4,3-d]pyrimidines 12, respectively. © 2006 Verlag der Zeitschrift für Naturforschung.
On New Staudinger Type Reactions of Phosphorus Centered Biradicaloids, [P(μ-NR)]2 (R = Ter, Hyp), with Ionic and Covalent Azides
Phosphorus centered biradicaloids of the type [P(μ-NTer)]2 [R = Ter = terphenyl = 2,6-bis(2,4,6-trimethylphenyl)phenyl, Hyp = tris(trimethylsilyl)silyl] were treated with covalent (R-N3) and ionic azides (AgN3 and Hg(N3)2). While the reaction with the ionic azides led exclusively to the formation of diazides, [N3P(μ-NTer)]2, triaza-diphospha-pentadienes, RN=P–N(R')–P=NR, were observed in the reaction with covalent azides featuring a Staudinger type reaction followed by PN bond rearrangement reactions. This new Staudinger type mechanism as well as the structure, bonding and thermodynamics along different reaction paths are discussed based on DFT computations.
Crystal structure of 1, 1-bis(pentamethylcyclopentadienyl)-4, 5-bis(trimethyIsilyl)-1-hafnafuran-3-one, Hf(C10H15) 2(Me3SiC2SiMe3CO2)
C29H48HfO2Si2, orthorhombic, Pnma (no. 62), a = 16.8546(4) Å= 14.4139(6) Å= 12.1421(3) Å, V= 2949.8 Å3, Z = 4, Rgt(F) = 0.020, WR ref(F2) = 0.041, T= 200 K. © by Oldenbourg Wissenschaftsverlag.
Crystal structures of 1-2-(dicyclohexylphosphinophenyl)pyrol-2- dicyclohexylphosphino-rhodium(I) norborna-2,5-diene tetrafluoroborate tetrahydrofuran hemisolvate, [Rh(C34H5INP 2)(C7H8)] [BF4] · 0.5C 4H8O, and 1-2-(dicyclohexylphosphinophenyl)-pyrol-2- dicyclohexylphosphino-rhodium(I) (Z,Z)-cycloocta...
Title full: Crystal structures of 1-2-(dicyclohexylphosphinophenyl)pyrol-2- dicyclohexylphosphino-rhodium(I) norborna-2,5-diene tetrafluoroborate tetrahydrofuran hemisolvate, [Rh(C34H5INP 2)(C7H8)] [BF4] · 0.5C 4H8O, and 1-2-(dicyclohexylphosphinophenyl)-pyrol-2- dicyclohexylphosphino-rhodium(I) (Z,Z)-cycloocta-1,5-diene tetrafluoroborate, [Rh(C34H5INP2)(C8H12)] [BF4]. C43H63BF4NO0.50P2 Rh, monoclinic, P121/n1 (no. 14), a = 10.341(2) Å, b = 16.063(3) Å, c = 27.425(5) Å, β = 98.76(3)°, V= 4502.4 Å3, Z = 4, Rgt(F) = 0.060, wRref(F 2) = 0.143, T = 200 K. C42H63BF 4NP2Rh, monoclinic, P121/c1 (no. 14), a = 10.503(2) Å, b = 17.665(4) Å, c = 21.946(4) Å, β = 101.95(3)°, V= 3983.5 Å3, Z = 4, Rgt(F) = 0.045, wRref(F2) = 0.013, T =200 K. © by Oldenbourg Wissenschaftsverlag,.
Crystal structure of tris[(diphenylphosphino)methylene)- diphenylphosphoranylmethyl]yttrium diethyl ether monosolvate, [Y{P(C6H5)2CHP(C6H5)2CH2}3] (C2H5)2O
C82H79OP6Y, monoclinic, P12/cl (no. 13), a = 24.392(5) Å,b= 12.632(2) Å, c = 23.709(5) Å, β = 100.97°, V = 7171.8 Å3, Z = 4, Rgt(F) = 0.054, wRref(F2) = 0.112, T = 200 K.
Crystal structure of bis(η5-cyclopentadienyl)-pyrrolide- titanium(III), Ti(C10H15)2(C4H 4N)
C24H34NTi, orthorhombic, Pbcm (no. 57), a = 10.864(2) Å, b = 14.281(3) Å, c = 27.535(6) Å, V= 4272.0 Å3, Z = 8, Rgt(F) = 0.043, wRref(F 2) = 0.111, T= 200 K. © by Oldenbourg Wissenschaftsverlag,.
Crystal structure of dichloro((S)-2-(anilinomethyl)-pyrrolidine)- palladium(II), Pd(Cl)2(C11H16N2)
C11H16Cl2N2Pd, orthorhombic, P212121 (no. 19), a = 11.246(2) Å, b = 12.222(2) Å, c = 19.637(4) Å, V= 2699.1 Å3, Z = 8, Rgt(F) = 0.027, wRref(F2) = 0.060, T =200 K. © by Oldenbourg Wissenschaftsverlag,.
Crystal structure of [1,2-ethylene-1,1′ -bis(η5-tetrahydroindenyl)]-chloro- [η2-N,C-3,4,5,6-tetrafluoropyridyI]zirconium(IV), ZrCl(C5F4N)(C20H24)
C25H24Clf4NZr, monoclinic, P121/n1 (no. 14), a = 9.903(2) Å, b= 11.279(2) Å, c = 20.231(4) Å, β = 92.43(3)°, V = 2257.7 Å3, Z = 4, Rgt(F) = 0.035, wRobs(F2) = 0.076, T = 200 K.
Crystal structures of tribromo(η5-3,6-di-tert-butyl-9,10,11- trimethyl-bicyclo(6.3.0)undeca-4-en-8,10-dienyl)titanium(IV), Ti(C 22H35)Br3, and tribromo(η5-4,5- dibromo-3,6-di-tert-butyl-9,10,11-trimethyl-bicyclo(6.3.0)undeca-8,10-dienyl) titanium(IV), Ti(C22H35Br2)Br3
C22H35Br3Ti, triclinic, P1̄ (no. 2), a = 9.621(2) Å, b = 11.796(2) Å, c = 12.232(2) Å, α = 102.23(3)°, β = 97.71(3)°, γ = 112.32(3)°, V = 1219.2 Å3, Z = 2, Rgt(F) = 0.058, wRobs(F 2) = 0.134, T = 293 K. C22H35Br5Ti, monoclinic, P121/n1 (no. 14), a = 7.474(1) Å, b = 18.458(4) Å, c = 20.171(4) Å, β = 100.28(3)°, V= 2738.0 Å3, Z = 4, Rgt(F) = 0.054, wRobs(F 2) = 0.119, T = 293 K. © by Oldenbourg Wissenchaftsverlag.
Isolation of phytochemical constituents from hunteria umbellata k. Schum
Hunteria umbellata K. Schum has been reported for the treatment of diabetes in Nigeria. In the present study, the ethanolic extract of dried leaves of Hunteria umbellata K. Schum was investigated for the chemical principles. The isolated pure compounds were characterized by NMR, IR and Mass spectral studies. Ursolic acid (1), oleanolic acid (2) and squalene (3) were the main constituents isolated from the extract.
- 1 (current)
- 2
- 3
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