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91.
A total synthesis of d-(+)-biotin is described starting from d-(+)-glucosamine using acyliminium chemistry. 相似文献
92.
Gonnade RG Bhadbhade MM Shashidhar MS 《Chemical communications (Cambridge, England)》2004,(22):2530-2531
myo-Inositol hexabenzoate having meso configuration produces chiral polymorph (form I) when crystallized rapidly but yields achiral polymorph (form II) when allowed to crystallize slowly; in the mother liquor form I slowly but completely disappears to give form II. 相似文献
93.
R. Anjibabu Samaresh Sau B. Jagan Mohan Reddy Rajkumar Banerjee B.V. Subba Reddy 《Tetrahedron letters》2013
A variety of aldehydes undergo a smooth coupling with (4-methylcyclohex-3-en-1-yl)methanol in the presence of 2 mol % of phosphomolybdic acid in dichloromethane to afford 3-oxabicyclo[3.3.1]non-7-ene in good yields through 3,5-oxonium-ene cyclization under mild conditions. The use of inexpensive, nontoxic, and readily available heteropoly acid catalyst makes this method simple, convenient, and environmental-friendly. 相似文献
94.
[reaction: see text] A novel, mild, ecofriendly protocol for the deoxygenation of epoxides to alkenes using indium metal and indium(I) chloride or ammonium chloride in alcohol has been developed. It was necessary for the presence of good radical-stabilizing groups adjacent to the oxirane ring for the deoxygenation reaction to occur. It is proposed that this reaction occurs through an SET process with indium as an electron donor. 相似文献
95.
Venkatapuram Padmavathi Pinnu Thriveni Boggu Jagan Mohan Reddy Adivireddy Padmaja 《Journal of heterocyclic chemistry》2005,42(1):113-116
A new class of five membered heterocycles, thiadiazoles, triazoles and oxadiazoles were prepared from sulfonyl acetic acids via acid hydrazides. 相似文献
96.
Patwa AN Gonnade RG Kumar VA Bhadbhade MM Ganesh KN 《The Journal of organic chemistry》2010,75(24):8705-8708
X-ray crystallographic studies of methylene linked Ferrocene-bis(thymine/uracil) conjugates Fc(T:T)(M) and Fc(U:U)(M) reveal base dependent 2-D supramolecular assemblies generated via wobble self-pairing for bis-thymine and reverse wobble self-pairing for bis-uracil conjugates, differing in architecture from the corresponding butylene spacer linked conjugates. 相似文献
97.
Reaction of the benzene-linked bis(pyrazolyl)methane ligands, 1,4-bis{bis(pyrazolyl)-methyl}benzene (L1) and 1,4-bis{bis(3-methylpyrazolyl)methyl}benzene (L2), with pentamethylcyclopentadienyl rhodium and iridium complexes [(η5-C5Me5)M(μ-Cl)Cl]2 (M = Rh and Ir) in the presence of NH4PF6 results under stoichiometric control in both, mono and dinuclear complexes, [(η5-C5Me5)RhCl(L)]+ {L = L1 (1); L2 (2)}, [(η5-C5Me5)IrCl(L)]+ {L = L1 (3); L2 (4)} and [{(η5-C5Me5)RhCl}2(μ-L)]2+ {L = L1 (5); L2 (6)}, [{(η5-C5Me5)IrCl}2(μ-L)]2+ {L = L1 (7); L2 (8)}. In contrast, reaction of arene ruthenium complexes [(η6arene)Ru(μ-Cl)Cl]2 (arene = C6H6, p-iPrC6H4Me and C6Me6) with the same ligands (L1 or L2) gives only the dinuclear complexes [{(η6-C6H6)RuCl}2(μ-L)]2+ {L = L1 (9); L2 (10)}, [{(η6-p-iPrC6H4Me)RuCl}2(μ-L)]2+ {L = L1 (11); L2 (12)} and [{(η6-C6Me6)RuCl}2(μ-L)]2+ {L = L1 (13); L2 (14)}. All complexes were isolated as their hexafluorophosphate salts. The single-crystal X-ray crystal structure analyses of [7](PF6)2, [9](PF6)2 and [11](PF6)2 reveal a typical piano-stool geometry around the metal centers with six-membered metallo-cycle in which the 1,4-bis{bis(pyrazolyl)-methyl}benzene acts as a bis-bidentate chelating ligand. 相似文献
98.
The samples of natural mica (muscovite and biotite) were irradiated with energetic heavy ions [136Xe (11.56 MeV/n) and 197Au (11.40 MeV/n)] from universal linear accelerator (UNILAC) GSI, Darmstadt, Germany. The simple track etch technique has been used to develop and analyze the morphology of induced heavy ions and natural alpha recoil tracks with the help of atomic force microscopy. Defective structure and lattice disorder have been observed in the environs of the etch pits in these layered crystalline materials. The distribution of defects produced along the tracks, geometrical analysis of tracks shapes and shallowness and their correlations with the structural arrangement of the materials have been discussed in the present investigation. Importance of different ion track geometries in micaceous minerals for the fabrication of nanoterrace material with different stacks having sharp edges with unique properties has been elaborated in the present paper. 相似文献
99.
100.
(R)‐12‐Hydroxystearic Acid Hydrazides as Very Efficient Gelators: Diffusion,Partial Thixotropy,and Self‐Healing in Self‐Standing Gels 下载免费PDF全文
The gelation properties of derivatives of N‐alkylated (R)‐12‐hydroxystearic acid hydrazide (n‐HSAH, n=0, 2, 6, 10; n is the length of an n‐alkyl chain on the terminal nitrogen atom) in a wide variety of liquids is reported. The n‐HSAH compounds were derived from a naturally occurring alkanoic acid, (R)‐12‐hydroxystearic acid (R‐12HSA), and although they differ from the analogous N‐alkyl (R)‐12‐hydroxystearamides (n‐HSAA) only by the presence of one N?H group, their behavior as gelators is very different. For example, the parent molecule (0‐HSAH) is a supergelator in ethylene glycol, in which it forms self‐standing gels that are self‐healing, partially thixotropic, moldable, and load‐bearing; gels of 0‐HSAA are not self‐standing. 0‐HSAH is structurally the simplest molecular gelator of which we are aware that is capable of forming both self‐standing and partially thixotropic gels. Also, diffusion of the cationic dye erythrosine B and the anionic dye methylene blue in 0‐HSAH/ethylene glycol gel blocks is much slower than the self‐diffusion of ethylene glycol. Polarizing optical microscopy, X‐ray diffraction, and FTIR studies revealed that the self‐assembled fibrillar networks (SAFINs) of the gels are crystalline, and that 0‐HSAH molecules may be arranged in a triclinic subcell with bilayer stacking. The SAFINs are stabilized by strong hydrogen‐bonding interactions between the hydrazide groups of adjacent molecules and a perpendicular hydrogen‐bonding network between the pendent hydroxyl groups of 0‐HSAH. The other n‐HSAH (n=2, 6, 10) molecules appear to be arranged in orthorhombic subcells with monolayers and strong hydrogen‐bonding interactions between the hydrazide group of one gelator molecule and the hydroxyl group of a neighboring one. These results show how small structural modifications of structurally simple gelator molecules can be exploited to form gels with novel properties that can lead potentially to valuable applications, such as in drug delivery. 相似文献