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111.
Tushar Kanti Chakraborty Vakiti Ramkrishna Reddy Praveen Kumar Gajula 《Tetrahedron》2008,64(22):5162-5167
For the total synthesis of (−)-clavosolide A described herein, a Schmidt glycosidation reaction was used to attach the sugar moiety at an early stage in the synthesis to the 4-hydroxy group of the substituted tetrahydropyran unit of the molecule, which itself was built following a Ti(III)-mediated method developed by us earlier, and at the end, it was the Yamaguchi reaction that was successfully employed for the cyclodimerization of the two halves of the molecule leading to its total synthesis. 相似文献
112.
The total synthesis of hyptolide, a naturally occurring α,β-unsaturated six-membered δ-lactone substituted with a polyoxygenated chain, is described. Sharpless kinetic resolution and opening of two different epoxy alcohols under two different conditions—Swern oxidation conditions and a radical reaction using Cp2TiCl—fixed the stereocenters at C-9, C-11, and C-12, respectively. Brown’s asymmetric allylation reaction installed the remaining stereocenter at C-6. A RCM protocol was used for construction of the α,β-unsaturated six-membered δ-lactone moiety of the molecule. 相似文献
113.
Tushar S. Basu Baul Archana Mizar Ulli Englert 《Journal of organometallic chemistry》2008,693(10):1751-1758
Reactions of sodium 5-[(E)-2-(aryl)-1-diazenyl]quinolin-8-olates (LH, where the aryl group is an R-substituted phenyl ring such that for L1H: R = H; L2H: R = 2′-CH3; L3H: R = 3′-CH3; L4H: R = 4′-CH3; L5H: R = 4′-OCH3 and L6H: R = 4′-OC2H5) with Ph3SnCl in a 1:1 molar ratio yielded complexes of composition Ph3SnL. The complexes have been characterized by 1H, 13C, 119Sn NMR, IR and 119mSn Mössbauer spectroscopic techniques in combination with elemental analyses. The crystal structures of Ph3SnL1 · 0.5C6H6 (1), Ph3SnL2 (2), Ph3SnL5 · C6H6 (5) and Ph3SnL6 · 0.5C6H6 (6) were determined. The results of the X-ray studies indicated that the benzene solvated compounds 1, 5 and 6 are distorted square pyramid, with one of the phenyl C atoms in the apex while the ligand arrangement around central Sn atom in 2 is distorted trigonal-bipyramidal, with a phenyl C and the oxinato N atoms in axial positions. 相似文献
114.
An accurate and reproducible liquid chromatographic assay method was developed and validated for the determination of nebivolol and valsartan in a capsule formulation. Buffer-acetonitrile (55 + 45, v/v) was used for reversed-phase liquid chromatography to determine the contents of nebivolol and valsartan in the combination-capsule dosage form. The method was validated by determining parameters such as specificity, linearity, limits of detection and quantitation, precision, accuracy, and robustness. The method was found to be specific against placebo interference. Linearity was evaluated over the concentration ranges of 2-8 micro/mL for nebivolol and 32-128 microg/mL for valsartan (the correlation coefficient was 0.9999 for both nebivolol and valsartan). Both the intraday and interday precision values of the system and the method were determined. The accuracy of the method ranged from 100.66 to 102.58% for nebivolol and from 101.17 to 101.85% for valsartan. The proposed method was found to be robust when slight but deliberate changes were made in the analytical conditions. The developed method was found suitable for the assay determination of nebivolol and valsartan in a capsule formulation. 相似文献
115.
116.
Marat R. Talipov Tushar S. Navale Rajendra Rathore 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(48):14676-14680
Triptycenes spontaneously assemble into two‐dimensional networks in which long‐range charge transport is facilitated by the extensive electronic coupling through the triptycene framework (intramolecularly) and by cofacial π‐stacking (intermolecularly). While designing and synthesizing next‐generation triptycenes containing polyaromatic chromophores, the electronic coupling amongst the chromophores was observed to be highly dependent on the nature and position of the substituents. Herein, we demonstrate using hexaalkoxytriptycenes that the electronic coupling amongst the chromophores is switched on and off by a simple repositioning of the substituents, which alters the nodal arrangement of the HOMOs of the individual chromophores. A visual inspection of the HOMOs can thus provide a ready evaluation of the electronic coupling in polychromophoric molecules/assemblies, and will serve as an important tool for the rational design of modern charge‐transport materials. 相似文献
117.
118.
Rajesh Malhotra Sagar Chakrabarti Amit Ghosh Rajib Ghosh Tushar K. Dey Swarup Dutta Shantanu Dutta Subho Roy Sourav Basu Saumen Hajra 《Tetrahedron: Asymmetry》2013,24(5-6):278-284
A divergent and scalable asymmetric synthesis of the dopamine D1 agonists, A-86929, and dihydrexidine with high diastereo- and enantioselectivity was accomplished from Weinreb amide 8 derived from inexpensive and easily available l-serine. The synthesis of A-86929 involves only one chromatographic purification. 相似文献
119.
Pranav Chandrachood Tushar Gadkari Nirmala Deshpande Rajashree Kashalkar 《Journal of the Iranian Chemical Society》2012,9(1):47-51
The oxidation of 1,4-dihydropyridines has been carried out using catalytic quantity of transition metal nitrates supported on silica gel under IR irradiation. The C-4 de-alkylation is found to be minimal due to milder reaction conditions. The new protocol has been found to be economic and environment friendly. 相似文献
120.
Tushar M. Khopade Prakash K. Warghude Trimbak B. Mete Ramakrishna G. Bhat 《Tetrahedron letters》2019,60(2):197-200
The operationally simple, robust and straightforward organocatalytic protocol is developed for the synthesis of E-selective α,β-unsaturated ketones. The method utilizes simple and easily accessible starting materials such as Meldrum’s acid, carboxylic acid, aldehyde and simple bifunctional amine catalyst. The tandem organocatalytic process utilizes acyl/aroyl Meldrum’s acid as an enol surrogate for the effective Doebner-Knoevenagel type condensation reactions. A wide variety of aldehydes, carboxylic acids and base sensitive functional groups are well tolerated under the mild reaction conditions. 相似文献