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131.
Vijaya D. Bharathi Kanbarpa Radharani Banda Jagadeesh Gajjela Ramulu Indu Bhushan Andra Naidu Ramesh Mullangi 《Chromatographia》2008,67(5-6):461-466
A rapid, sensitive, and simple HPLC–MS–MS method, with electro-spray ionization and cetirizine as internal standard (IS),
has been developed and validated for simultaneous quantification of fexofenadine and pseudoephedrine in human plasma. The
analytes were isolated from plasma by solid-phase extraction (SPE) on Oasis HLB cartridges. The compounds were chromatographed
on an RP 18 column with a mixture of ammonium acetate (10 mm, pH 6.4) and methanol as mobile phase. Quantification of the analytes was based on multiple reaction monitoring (MRM) of
precursor-to-product ion pairs m/z 502 → 466 for fexofenadine, m/z 166 → 148 for pseudoephedrine, and m/z 389 → 201 for cetirizine. The linear calibration range for both analytes was 2–1,700 ng mL−1 (r = 0.995), based on analysis of 0.1 mL plasma. Extraction recovery was 91.5 and 80.88% for fexofenadine and pseudoephedrine,
respectively. The method was suitable for analysis of human plasma samples obtained 72 h after administration of a drug containing
both fexofenadine and pseudoephedrine. 相似文献
132.
Dattatri Maneesh Kumar Reddy Singam Suresh Vavilapalli Jagadeesh Babu Nanubolu Dr. Maddi Sridhar Reddy 《Angewandte Chemie (International ed. in English)》2023,62(12):e202215825
The C−H functionalization strategy provides access to valuable molecules that previously required convoluted synthetic attempts. Dual C−H unsymmetrical functionalization, with a single bifunctional reagent, is an effective tactic. Propargyl alcohols (PAs), despite containing a reactive C≡C bond, have not been explored as building blocks via oxidative cleavage. Annulations via C−H activation are a versatile and synthetically attractive strategy. We disclose PA as a new bifunctional reagent for unsymmetrical dual C−H functionalization of biphenylamine for regioselectively annulated outcomes. On tuning the conditions, the annulation bifurcated towards an unusual dual oxidative cyclization. This method accommodates a wide range of PAs and showcases late-stage diversification of some natural products. 相似文献
133.
Venkata Bharat Nishtala Jagadeesh Babu Nanubolu Srinivas Basavoju 《Research on Chemical Intermediates》2017,43(3):1365-1381
Efficient synthesis of novel spirooxindolo and spiroquinoxalinopyrrolizidine derivatives was expediently accomplished with regioselectivity via one-pot, three-component 1,3-dipolar cycloaddition using ultrasonication. Chalcones derived from both heteroaryl methyl ketones and furfural were used as dipolarophiles in these reactions. The synthesized compounds were analyzed by 1H and 13C nuclear magnetic resonance (NMR), mass spectrometry, and elemental (CHN) analysis. Single-crystal X-ray diffraction studies of one of the compounds (11d) proved the structure and regiochemistry of the cycloaddition. The ultrasound methodology is clearly advantageous, and the desired products were obtained in moderate to good yield in shorter reaction time compared with conventional heating and fusion methods. 相似文献
134.
T.?SaitoEmail author V.?Menezes T.?Kuribayashi M.?Sun G.?Jagadeesh K.?Takayama 《Shock Waves》2003,13(5):327-337
The surface convective heat transfer rates to a cylinder have been measured using platinum thin film gauges in a shock tube and the results have been used to validate two numerical codes. The investigations have been carried out at different incident shock Mach numbers and flow Reynolds numbers. The measured and simulated results give an insight into the transient flow fields around the model in the shock tube and are a valuable means of complementing the numerical and experimental techniques used in this study.Received: 27 August 2003, Accepted: 11 November 2003, Published online: 17 February 2004Correspondence to: T. Saito 相似文献
135.
Krishnan Ravikumar Balasubramanian Sridhar Jagadeesh Babu Nanubolu Govindaraju Karthik Basi Venkata Subba Reddy 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(11):1001-1009
Spiro scaffolds are being increasingly utilized in drug discovery due to their inherent three‐dimensionality and structural variations, resulting in new synthetic routes to introduce spiro building blocks into more pharmaceutically active molecules. Multicomponent cascade reactions, involving the in situ generation of carbonyl ylides from α‐diazocarbonyl compounds and aldehydes, and 1,3‐dipolar cycloadditon with 3‐arylideneoxindoles gave a novel class of dispirooxindole derivatives, namely 1,1′′‐dibenzyl‐5′‐(4‐chlorophenyl)‐4′‐phenyl‐4′,5′‐dihydrodispiro[indoline‐3,2′‐furan‐3′,3′′‐indoline]‐2,2′′‐dione, C44H33ClN2O3, (I), 1′′‐acetyl‐1‐benzyl‐5′‐(4‐chlorophenyl)‐4′‐phenyl‐4′,5′‐dihydrodispiro[indoline‐3,2′‐furan‐3′,3′′‐indoline]‐2,2′′‐dione, C39H29ClN2O4, (II), 1′′‐acetyl‐1‐benzyl‐4′,5′‐diphenyl‐4′,5′‐dihydrodispiro[indoline‐3,2′‐furan‐3′,3′′‐indoline]‐2,2′′‐dione, C39H30N2O4, (III), and 1′′‐acetyl‐1‐benzyl‐4′,5′‐diphenyl‐4′,5′‐dihydrodispiro[indoline‐3,2′‐furan‐3′,3′′‐indoline]‐2,2′′‐dione acetonitrile hemisolvate, C39H30N2O4·0.5C2H3N, (IV). All four compounds exist as racemic mixtures of the SSSR and RRRS stereoisomers. In these structures, the two H atoms of the dihydrofuran ring and the two substituted oxindole rings are in a trans orientation, facilitating intramolecular C—H...O and π–π interactions. These weak interactions play a prominent role in the structural stability and aid the highly regio‐ and diastereoselective synthesis. In each of the four structures, the molecular assembly in the crystal is also governed by weak noncovalent interactions. Compound (IV) is the solvated analogue of (III) and the two compounds show similar structural features. 相似文献
136.
Rf magnetron sputtering technique was employed for preparation of tantalum oxide films on quartz and crystalline silicon (111) substrates held at room temperature by sputtering of tantalum in an oxygen partial pressure of 1x10‐4 mbar. The films were annealed in air for an hour in the temperature range 573 – 993 K. The effect of annealing on the chemical binding configuration, structure and optical absorption of tantalum oxide films was systematically studied. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
137.
Balasubramanian Sridhar Jagadeesh Babu Nanubolu Krishnan Ravikumar 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(7):602-609
Cocrystals are molecular solids composed of at least two types of neutral chemical species held together by noncovalent forces. Crystallization of thymine [systematic name: 5‐methylpyrimidine‐2,4(1H,3H)‐dione] with four phenolic coformers resulted in cocrystal formation, viz. catechol (benzene‐1,2‐diol) giving thymine–catechol (1/1), C5H6N2O2·C6H6O2, (I), resorcinol (benzene‐1,3‐diol) giving thymine–resorcinol (2/1), 2C5H6N2O2·C6H6O2, (II), hydroquinone (benzene‐1,4‐diol) giving thymine–hydroquinone (2/1), 2C5H6N2O2·C6H6O2, (III), and pyrogallol (benzene‐1,2,3‐triol) giving thymine–pyrogallol (1/2), C5H6N2O2·2C6H6O3, (IV). The resorcinol molecule in (II) occupies a twofold axis, while the hydroquinone molecule in (III) is situated on a centre of inversion. Thymine–thymine base pairing is common across all four structures, albeit with different patterns. In (I)–(III), the base pair is propagated into an infinite one‐dimensional ribbon, whereas it exists as a discrete dimeric unit in (IV). In (I)–(III), the two donor N atoms and one carbonyl acceptor O atom of thymine are involved in thymine–thymine base pairing and the remaining carbonyl O atom is hydrogen bonded to the coformer. In contrast, in (IV), just one donor N atom and one acceptor O atom are involved in base pairing, and the remaining donor N atom and acceptor O atom of thymine form hydrogen bonds to the coformer molecules. Thus, the utilization of the donor and acceptor atoms of thymine in the hydrogen bonding is influenced by the coformers. 相似文献
138.
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140.
Visible‐Light/Photoredox‐Mediated sp3 CH Functionalization and Coupling of Secondary Amines with Vinyl Azides in Flow Microreactors 下载免费PDF全文
Dr. Dharmendra Kumar Tiwari Dr. Ram Awatar Maurya Dr. Jagadeesh Babu Nanubolu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):526-530
Structurally diverse imidazole derivatives were synthesized by a visible‐light/[Ru(bpy)3][(PF6)2]‐mediated coupling of vinyl azides and secondary amines in flow microreactors. This operationally simple and atom‐economical protocol allows the formation of three new C?N bonds through the functionalization of sp3 C?H bonds adjacent to the secondary nitrogen atom. In order to get mechanistic insight of the coupling reaction, several control experiments were carried out and discussed. 相似文献