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101.
AbstractA stereoselective total synthesis of 16-membered C2-symmetric macrodiolide Pyrenophorol, Tetrahydropyrenophorol and 4,4-diacetylpyrenophorol have been accomplished. The synthesis started from commercially available L-Aspartic acid and the key reactions involved are regioselective epoxide opening, CBS reduction, Pinnick oxidation and Mitsunobu dilactonization. 相似文献
102.
The investigated reaction of 4-chloro-2H-chromene-3-carbaldehyde 1a with ethyl 3-oxobutanoate 2a in the presence of ammonium acetate provided two compounds, 2H-chromenyldihydropyridine dicarboxylate 3a and chromenopyridine carboxylate 4a. However, the reaction of 1a with ethyl-3-aminocrotonate 5a in the presence of p-TsOH provided selectively 2H-chromenyldihydropyridine dicarboxylate 3a with very good yield. The established method was applied for the preparation of series of 2H-chromenyldihydropyridine dicarboxylates 3a–q. 相似文献
103.
Studies on pyrimidine derivatives. Michael addition of β-nitrostyrenes to substituted 6-aminouracils
A series of 5-(2-nitro-l-phenyl)ethyluracils were obtained when β-nitrostyrenes were reacted with 1,3-di-methyl-6-substituted uracil derivatives, instead of cyclic compounds. The structures of the compounds 5, 6 , and 7 were proved by spectroscopic methods and their mass fragmentation patterns are discussed. 相似文献
104.
Reddy SL Fayazuddin M Reddy NC Ahmad A Reddy GS Rao PS Reddy BJ Frost RL 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(1):31-38
Leaves of bhringaraj and guduchi herb of Kadapa district of Andhra Pradesh, India, are dried and powdered. ICP-MS analysis of samples indicates that copper is present in both the samples. An EPR study of guduchi sample also confirms the presence of Fe(III) whereas Eclipta alba confirms the presence of Fe(III), Mn(II) and Cu(II). Optical absorption spectrum of guduchi indicates that Cu(II) is present in rhombically distorted octahedral environment. NIR and IR results are due to carbonate fundamentals. 相似文献
105.
4H-Chromenyl-tetrahydro-2H-pyrancarboxylates 3a–k have been conveniently prepared by the reaction of 3-formylchromones 1a–k and ethyl 4,4,4-trifluoro-3-oxobutanoate 2a with good yields. Thus obtained 4H-chromenyl-tetrahydro-2H-pyrancarboxylates 3a–k were reacted with amines 4a–e to provide series of 5-(2-hydroxybenzoyl)-2-(trifluoromethyl)-1,2-dihydropyridine-3-carboxylates 5a–o. The reaction proceeded via Michael addition (C-N bond formation) and followed by cleavage of chromone and pyran rings (C-O bond cleavage) in one pot. 相似文献
106.
Sanjay Dashrath Vaidya Bobba Venkata Siva Kumar Ramanatham Vinod Kumar Umesh Nanasaheb Bhise Uday Chandrakant Mashelkar 《Journal of heterocyclic chemistry》2007,44(3):685-691
107.
Mimicking the Energy Funnel of the Photosynthetic Unit Using a Dendrimer-Dye Supramolecular Assembly
V. Siva Rama Krishna Soumen Adak Palash Jana Varun Bheemireddy Subhajit Bandyopadhyay 《化学:亚洲杂志》2021,16(21):3481-3486
Photosynthesis involves light-harvesting complexes where an array of antenna pigment channels the absorbed solar energy to the reaction centre of a photosystem. This work reports a supramolecular dendrimer-dye assembly that mimics the natural light-harvesting mechanism. A dendrimeric molecule based on two-fluorophores has been constructed with three coumarin units at the end of three long arms and a 7-diethylaminocoumarin unit at the interior. The molecule self-aggregates in water into spherical micelles, which can encapsulate a rose-bengal dye (RB). On excitation, peripheral coumarin units shuttled the energy to the loaded RB dye reaction center via a two-step cascade resonance energy transfer (RET). The energy absorbed in the periphery is funnelled efficiently, resulting in a strong emission from the dye that resembles an energy funnel. The energy transfer cascade has been studied with both steady-state and time-resolved fluorescence spectroscopy. Molecular dynamics simulations of the self-assembled aggregates in water were also in agreement with the experimental observations. 相似文献
108.
Siva Rama Kasibabu Velugula Aaramadaka Sunil Kumar Reddy Nimesh Chandra Misra Pindi Santhosh Reddy Ramadas Chavakula Anil Kumar Guduri Paul Douglas Sanasi 《Journal of heterocyclic chemistry》2021,58(8):1581-1587
Oxcarbazepine is a drug substance used to treat epilepsy. During its bulk synthesis of various impurities formation will be observed. Herein we describe the formation, synthesis and characterization of four potential impurities, namely, N-acetyl Oxcarbazepine, N-formyl Oxcarbazepine, N-carbamoyl Oxcarbazepine, and Oxcarbazepine dimer. These impurities are listed in several Pharmacopoeias and the control of these impurities below the threshold level is essential. Our study will be a guide for making these reference standards. 相似文献
109.
Dogamanti Ashok Chiranjeevi Pamula Aamate Vikas Kumar Vagolu Siva Krishna Sriram Dharmarajan Balasubramanian Sridhar Sarasija Madderla 《Molecular diversity》2021,25(4):2137-2148
Molecular Diversity - As part of an ongoing effort to develop new anti-tubercular agents, a series of novel indole-fused spirochromene hybrids (7a–l) were efficiently synthesized in excellent... 相似文献
110.
The synthesis of one-dimensional titanium oxide nanostructures has been accelerated by performing the reaction in a microfluidic environment as opposed to a classical batch process. 相似文献