排序方式: 共有26条查询结果,搜索用时 46 毫秒
1.
Biswanath Das D. Nandan Kumar Keetha Laxminarayana B. Ravikanth 《Helvetica chimica acta》2007,90(7):1330-1334
The synthesis of 14‐aryl‐ or 14‐alkyl‐14H‐dibenzo[a,j]xanthenes 3 involving the treatment of naphthalen‐2‐ol ( 1 ) with arenecarboxaldehydes or alkanals 2 in the presence of HClO4?SiO2 as a heterogeneous catalyst was achieved (Table 1), and this reaction was extended to the preparation of N‐[(2‐hydroxynaphthalen‐1‐yl)methyl]amides 5 by a three‐component reaction with urea ( 4a ) or an amide 4b – d as a third reactant (Table 2). 相似文献
2.
Biswanath Das Maddeboina Krishnaiah Keetha Laxminarayana K. Ravinder Reddy 《Journal of molecular catalysis. A, Chemical》2007,270(1-2):284-288
Sulfated zirconia has been employed as an efficient recyclable catalyst for the preparation of various β-acetamidoketones or esters at room temperature. The process involves the one-pot multicomponent reactions of aromatic aldehydes, enolizable ketones or β-ketoesters and acetonitrile in the presence of acetyl chloride. 相似文献
3.
K. Raghavendra Rao Akula Raghunadh Ramamohan Mekala Suresh Babu Meruva T.V. Pratap T. Krishna Dipak Kalita Eppakayala Laxminarayana Bagineni Prasad Manojit Pal 《Tetrahedron letters》2014
A dual reactant/catalyst role of glyoxylic acid in the reaction of isatoic anhydride with various amines afforded a novel, robust and rapid synthesis of 3-(un)substituted quinazolin-4(3H)-ones. This metal catalyst-free reaction proceeds via an unusual and unexpected cleavage of C–C bond. A shorter and common route to two alkaloids, that is, rutaecarpine and evodiamine is also accomplished. 相似文献
4.
Biswanath Das Maddeboina Krishnaiah Ponnaboina Thirupathi Keetha Laxminarayana 《Tetrahedron letters》2007,48(24):4263-4265
A catalyst-free regio- and stereoselective ring-opening of epoxides with phenoxides has been carried out efficiently using polyethylene glycol as the reaction medium to form the corresponding β-aryloxyalcohols in high yields at room temperature. 相似文献
5.
Kumar B. Ravi Kumar A. Kishore Reddy B. Srinivas Shashikala K. Laxminarayana E. 《Russian Journal of Organic Chemistry》2022,58(4):580-583
Russian Journal of Organic Chemistry - tert-Butyl 4-[(E)-but-1-en-3-yn-1-yl]-3-{[tert-butyl(dimethyl)silyl]oxy}-1H-indole-1-carboxylate has been synthesized with a good yield and selectivity... 相似文献
6.
Mohan G. Sridhar G. Laxminarayana E. Chary M. T. 《Russian Journal of Organic Chemistry》2021,57(9):1495-1500
Russian Journal of Organic Chemistry - A series of N-[2-(4-methoxyanilino)-5-(3,4,5-trimethoxyphenyl)pyridin-3-yl]benzamides have been synthesized, and their structure was confirmed by 1H and 13C... 相似文献
7.
Biswanath Das Yallamalla Srinivas Harish Holla Keetha Laxminarayana Ravirala Narender 《Tetrahedron letters》2007,48(38):6681-6683
Polymethylhydrosiloxane (PMHS) in combination with (bromodimethyl)sulfonium bromide or NBS has been utilized for the first time for reductive bromination of aromatic aldehydes at room temperature to afford the corresponding benzyl bromides in excellent yields. 相似文献
8.
Eppakayala Sreedhar R. Sateesh Chandra Kumar G. Venkateswar Reddy A. Robinson K. Suresh Babu J. Madhusudana Rao P.V. Srinivas 《Tetrahedron: Asymmetry》2009,20(4):440-448
A concise total synthesis of neohelmanticins A–D has been accomplished in 15 steps starting from commercially available gallic acid. Swern oxidation conditions, a Grignard reaction, Sharpless kinetic resolution, and regioselective ring opening of an epoxide with lithium aluminum hydride (LAH) are the key features to install the basic core, dihydroxy phenyl propane 2. One hydroxyl group of this core was esterified with tiglic acid followed by the oxidation and esterification with corresponding acids to yield neohelmanticins A–D. 相似文献
9.
Arramshetti Venkanna Eppakayala Sreedhar Bandi Siva Katragadda Suresh Babu Kothakonda Rajendra Prasad Janaswamy Madhusudana Rao 《Tetrahedron: Asymmetry》2013,24(17):1010-1022
The stereoselective synthesis of the macrolactone core of the natural product koshikalide is described. Starting with readily available 1,4-butanediol and malic acid as synthons, our synthetic strategy involved the reiterative application of Gilman’s reaction, Swern oxidation and Sharpless asymmetric epoxidation to establish the required stereocentres. Other key steps in the synthesis include Negishi cross coupling and Horner–Wadsworth–Emmons (HWE) reactions for construction of the main fragments. The 14-membered lactone ring was prepared by a selective Mitsunobu macrolactonization approach. 相似文献
10.
Biswanath Das Maddeboina Krishnaiah Vtukuri Saidi Reddy Keetha Laxminarayana 《Helvetica chimica acta》2007,90(11):2163-2166
Treatment of different types of alcohols with tetrahydrofuran (THF) in the presence of VCl3 and CCl4 smoothly afforded the corresponding THF‐based acetals in excellent yields. The reaction is fast at room temperature, and several functional groups are tolerated, with no racemization being observed. A radical mechanism, based on Cl3C. as the active species, is proposed for this novel kind of transformation, which complements the classical tetrahydro‐2H‐pyran‐2‐yl (THP) protocol. 相似文献