70384-80-4Relevant articles and documents
Synthesis, characterization and antioxidant activity studies of new coumarin tethered 1,3,4-oxadiazole analogues
Achutha, Dileep Kumar,Basappa, Vagish Channa,Kariyappa, Ajay Kumar,Penubolu, Sudeep
, (2021/06/01)
The present work describes the synthesis of a series of substituted 3-(5-phenyl-1,3,4-oxadiazol-2-yl)-2H-chromen-2-ones 7(a–j) using substituted aldehydes with analogues of hydrazine hydrates by grinding technique in the presence of Iodine which helps in the cyclization process. The structures of the synthesized compounds were elucidated by spectroscopic techniques such as IR, 1H NMR, 13C NMR, and LCMS. The comparative antioxidant property (using DPPH and hydroxyl radical scavenging) has been studied with the synthesized compounds 7(a-j) and the standards. Compounds 7d and 7i show the prominent radical scavenging activity. Graphic abstract: [Figure not available: see fulltext.] Synopsis: Series of ten new coumarin-oxadiazole hybrids synthesized in three steps starting from salicylaldehyde and diethylmalonate. All new compounds were spectroscopically characterized. The results of radical scavenging activities show that, two compounds of the series 7d and 7i displayed potent DPPH and hydroxyl radical activity comparable to the standards employed, and therefore acts as antioxidant leads.
A facile, efficient and solvent-free titanium (IV) ethoxide catalysed knoevenagel condensation of aldehydes and active methylenes
Ramaiah, Manjunatha M.,Shivananju, Nanjunda Swamy,Shubha, Priya Babu
, p. 107 - 115 (2020/02/04)
Titanium ethoxide has been employed as a novel and efficient reagent for the Knoevenagel condensation of aldehydes with active methylenes such as diethyl malonate and ethyl cyanoacetate under solvent free conditions to afford substituted olefins in high to excellent yields. The reaction is suitable for a variety of aromatic, aliphatic and heteroaromatic aldehydes with various active methylenes. Parallel to this, microwave irradiation has been utilized to achieve improved reaction rates and enhanced yields. Herein, we illustrated a convenient method for the preparation of α,β-unsaturated compounds using both conventional and microwave irradiation methods. An efficient and solvent free Knoevenagel condensation between aldehydes and active methylenes was developed using titanium ethoxide. The procedure proved to be successful with a wide range of substrates such as aromatic, aliphatic and heterocyclic aldehydes and various active methylenes to afford substituted olefins. The reaction was also carried out under microwave irradiation to accomplish the corresponding olefins with improved reaction rates, yields and cleaner reaction profiles.We have developed an efficient and novel methodology for the synthesis of olefinic compounds by Knoevenagel condensation under solvent-free conditions using titanium ethoxide, for the first time, as a reagent as well as a solvent. This method is appropriate for the synthesis of a variety of aromatic aldehydes containing various electron-donating and withdrawing groups, aliphatic and heteroaromatic aldehydes. The significant advantages offered by this methodology could be applied to various active methylenes in order to offer the corresponding Knoevenagel products. Thus, we believe that this method delivers high conversions, cleaner reaction profiles under solvent-free reaction conditions and shorter reaction times, all of which make it a very useful and attractive approach for the preparation of a wide range of substituted olefins.
A sustainable innovation for the tandem synthesis of sugar-containing coumarin derivatives catalyzed by lipozyme TL im from: Thermomyces lanuginosus in continuous-flow microreactors
Chen, Ping-Feng,Du, Li-Hua,Long, Rui-Jie,Luo, Xi-Ping,Xue, Miao
, p. 13252 - 13259 (2020/04/22)
We developed an efficient and environmentally friendly two-step tandem methodology for the synthesis of sugar-containing coumarin derivatives catalyzed by lipozyme TL IM from Thermomyces lanuginosus in continuous-flow microreactors. Compared to those observed for other methods, the salient features of this work including green reaction conditions, short residence time (50 min), and catalysts are more readily available and the biocatalysis reaction process is efficient and easy to control. This two-step tandem synthesis of coumarin derivatives using the continuous-flow technology is a proof of concept that opens the use of enzymatic microreactors in coumarin derivative biotransformations.
