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1.
Abstract A simple, efficient, and alternative synthetic route for docetaxel with better control on the protection–deprotection sequence has been developed. The process is easily scalable and commercially viable, and critical impurities can be controlled efficiently. For the first time, absolute configuration of docetaxel was determined unambiguously by single-crystal x-ray diffraction. 相似文献
2.
AlCl3 facilitated C-C bond forming reaction between 4-chloro-thieno[2,3-d]pyrimidines and (hetero)arenes affording a direct and single-step method for the synthesis of 4-(hetero)aryl substituted thieno[2,3-d]pyrimidines. A number of novel thienopyrimidines were prepared in good to excellent yields using this methodology. The molecular structure of a representative compound was established unambiguously by single crystal X-ray diffraction. 相似文献
3.
Murali Krishna Kolli Palani Elamathi Vishweshwar Rao Katta Gajendrasinh Balvantsinh Raolji 《合成通讯》2018,48(6):638-649
One-pot synthesis of α-aminophosphonates directly from aryl nitro compounds, aldehydes/ketones, and diethyl phosphite using sodium dithionite through reduction and followed by Kabachnik–Fields reaction under metal-free conditions is reported. The major advantages are excellent yield, high chemoselectivity, neutral reaction medium, and simple experimental procedure. This methodology consists of the following steps: 1) amine formation from nitro compound, 2) imine formation from amine and aldehyde/ketone, 3) phosphate addition to imine. 相似文献
4.
Peddy Vishweshwar Ashwini Nangia Vincent M Lynch 《The Journal of organic chemistry》2002,67(2):556-565
X-ray crystal structures of pyrazinic acid 1 and isomeric methylpyrazine carboxylic acids 2-4 are analyzed to examine the occurrence of carboxylic acid-pyridine supramolecular synthon V in these heterocyclic acids. Synthon V, assembled by (carboxyl)O-H...N(pyridine) and (pyridine)C-H...O(carbonyl) hydrogen bonds, controls self-assembly in the crystal structures of pyridine and pyrazine monocarboxylic acids. The recurrence of acid-pyridine heterodimer V compared to the more common acid-acid homodimer I in the crystal structures of pyridine and pyrazine monocarboxylic acids is explained by energy computations in the RHF 6-31G* basis set. Both the O-H.N and the C-H...O hydrogen bonds in synthon V result from activated acidic donor and basic acceptor atoms in 1-4. Pyrazine 2,3- and 2,5-dicarboxylic acids 10 and 11 crystallize as dihydrates with a (carboxyl)O-H...O(water) hydrogen bond in synthon VII, a recurring pattern in the diacid structures. In summary, the carboxylic acid group forms an O-H...N hydrogen bond in pyrazine monocarboxylic acids and an O-H...O hydrogen bond in pyrazine dicarboxylic acids. This structural analysis correlates molecular features with supramolecular synthons in pyridine and pyrazine carboxylic acids for future crystal engineering strategies. 相似文献
5.
P. Sudhakar R. Srivijaya B.R. Sreekanth P.K. Jayanthi Peddy Vishweshwar Moses J. Babu K. Vyas Javed Iqbal 《Journal of Molecular Structure》2008,885(1-3):45-49
Robustness of carboxylic acid–pyridine supramolecular heterosynthon was examined in three 1:2 binary co-crystals of 4,4′-bipyridine with monocarboxylic acids, (4,4′-bipyridine)·(dl-hydroxyphenylacetic acid)2, 1; (4,4′-bipyridine)0.5·(4-bromonaphthalene-1-carboxylic acid), 2 and (4,4′-bipyridine)0.5·(4-methylbenzoic acid), 3. All the three co-crystals form “two-component supermolecules” (consisting of one molecule of 4,4′-bipyridine and two molecules of the relevant carboxylic acid) stabilized through carboxylic acid–pyridine heterosynthons. Co-crystals 1 and 2 exhibits the expected carboxylic acid–pyridine dimer (heterodimer I) whereas co-crystal 3 forms a novel carboxylic acid–pyridine catemer (heterocatemer II). 相似文献
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7.
Vishweshwar P McMahon JA Oliveira M Peterson ML Zaworotko MJ 《Journal of the American Chemical Society》2005,127(48):16802-16803
The elusive form II of aspirin has been obtained during co-crystallization experiments with levetiracetam or acetamide, and it has been characterized by IR, DSC, HPLC, and single-crystal X-ray diffraction. 相似文献
8.
Crystal engineering of pharmaceutical co-crystals from polymorphic active pharmaceutical ingredients 总被引:2,自引:0,他引:2
Vishweshwar P McMahon JA Peterson ML Hickey MB Shattock TR Zaworotko MJ 《Chemical communications (Cambridge, England)》2005,(36):4601-4603
The carboxylic acid-primary amide supramolecular heterosynthon is exploited for the generation of pharmaceutical co-crystals that contain two active pharmaceutical ingredients that are polymorphic in their pure forms. 相似文献
9.
Kolli Murali Krishna Palani Elamathi Govindasamy Chandrasekar Katta Vishweshwar Rao 《Research on Chemical Intermediates》2020,46(2):1047-1064
Research on Chemical Intermediates - Nanoporous AlSBA-15 catalysts with different nSi/nAl ratios (41, 129, and 210) were synthesized using a hydrothermal method. These catalysts were characterized... 相似文献
10.
Supramolecular synthon polymorphism in 2 : 1 co-crystal of 4-hydroxybenzoic acid and 2,3,5,6-tetramethylpyrazine 总被引:1,自引:0,他引:1
Co-crystals of 4-hydroxybenzoic acid and 2,3,5,6-tetramethylpyrazine (2 : 1) exhibit the first supramolecular synthon polymorphism in a co-crystal; metastable anti-hierarchic polymorph I converts to stable hierarchic form II. 相似文献