A Green, Solvent-Free, Microwave-Assisted, High-Yielding YbCl<sub>3</sub>Catalyzed Deprotection of THP/MOM/Ac/Ts Ethers of Chalcone Epoxide and 2′-Aminochalcone and Their Sequel Cyclization
作者:Sumit Kumar、Nishant Verma、Iram Parveen、Naseem Ahmed
DOI:10.1002/jhet.2517
日期:2016.11
Under microwave and solvent‐free conditions, YbCl3 efficiently catalyzed the deprotection of tetrahydropyran‐2‐yl, methoxymethyl (MOM), acetyl, and tosyl groups and sequelcyclization of chalconeepoxide to 2‐hydroxyindanone and 2′‐aminochalcone to aza‐flavanone. The reaction afforded the products in excellent yield (78–99%) at 850 W microwave heating within 1–5 min under eco‐friendly conditions. The
Isoflavones are synthesized in an one-pot reaction by treating the hypervalent iodine(III) reagent, [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser's reagent) with 2'-benzoyloxychalcones in McOH. A combined use of (diacetoxyiodo)benzene (DIB)/p-toluenesulfonic acid (TsOH) is also effective for the same purpose. As an extension of these monomeric reagents, polymer-supported DIB PSDIB, poly[4-(diacetoxy)iodo]styrene}
An environmentally benign synthesis of aurones and flavones from 2′-acetoxychalcones using n -tetrabutylammonium tribromide
作者:Gopal Bose、Ejabul Mondal、Abu T Khan、Manob J Bordoloi
DOI:10.1016/s0040-4039(01)01938-4
日期:2001.12
A wide variety of aurones (3a-f) can be prepared exclusively from 2'-acetoxychalcones (1a-f) in high yields in two steps, by bromination using n-tetrabutylammonium tribromide (TBATB) in the presence of CaCO3 in CH2Cl2-MeOH (5:2) at 0-5 degreesC followed by cyclization of the brominated. products 2a-f on treating with 0.2 M ethanolic KOH solution at 0-5 degreesC, respectively. In contrast various flavone derivatives 6a-f can be obtained exclusively from compounds 1a-f in fairly good yields, by brominating with the same reagent in CH2Cl2, followed by dehydrobromination and finally cyclization on treating with 0.1 M NaOMe solution. (C) 2001 Elsevier Science Ltd. All rights reserved.
Reaction of chalcones with N-bromosuccinimide. Synthesis of aurones
作者:D. Litkei、V. P. Khilya、A. L. Tokesh、Sh. Antush、A. V. Turov