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
Stereoselective synthesis of flavonoids. Part 7. Poly-oxygenated β-hydroxydihydrochalcone derivatives
作者:Reinier J.J. Nel、Hendrik van Rensburg、Pieter S. van Heerden、Johan Coetzee、Daneel Ferreira
DOI:10.1016/s0040-4020(99)00554-2
日期:1999.8
Epoxidation of a series of poly-oxygenated chalcones with urea-hydrogen peroxide complex in THF in the presence of DBU and poly-(l)- or -(d)-leucine, followed by TBTH/AIBN catalysed ring opening, afforded β-hydroxydihydrochalcones in moderate to high enantiomeric excess and yield. This represents the first stereoselective route towards this group of flavonoids.
Enantioselective synthesis of flavonoids. Part 51. Poly-oxygenated β-hydroxydihydrochalcones
作者:Reinier J.J. Nel、Pieter S. van Heerden、Hendrik van Rensburg、Daneel Ferreira
DOI:10.1016/s0040-4039(98)01064-8
日期:1998.7
Epoxidation of a series of poly-oxygenated chalcones with urea-hydrogen peroxide complex in THF in the presence of DBU and poly-(l)- or -(d)-leucine, followed by TBTH/AIBN catalysed ringopening, afforded β-hydroxydihydrochalcones in moderate to high enantiomeric excess and yield.
The first enantioselective synthesis of trans- and cis-dihydroflavonols
作者:Hendrik van Rensburg、Pieter S. van Heerden、Barend C. B. Bezuidenhoudt、Daneel Ferreira
DOI:10.1039/cc9960002747
日期:——
Epoxidation of a series of polyoxygenated chalcones with H2O2 in the presence of poly(α-amino acid) catalysts, followed by Lewis acid-catalysed phenylmethanethiol ring-opening and cyclization, afforded trans- and cis-dihydroflavonols in moderate to high enantiomeric excess and yield.
Stereoselective synthesis of flavonoids. Part 4. Trans- and cis-dihydroflavonols
作者:Hendrik van Rensburg、Pieter S. van Heerden、Barend C.B. Bezuidenhoudt、Daneel Ferreira
DOI:10.1016/s0040-4020(97)00916-2
日期:1997.10
Epoxidation of a series of poly-oxygenated chalcones with H2O2 in the presence of poly-α-aminoacids yielded chiral aromatic oxygenated oxiranes in moderate to high optical yields. Lewis acid-catalysed phenylmethanethiol ringopening of the epoxide functionality and subsequent formation of the pyranone heterocycle, afforded trans- and cis-dihydroflavonols in moderate to high enantiomeric excess and yield
在聚-α-氨基酸的存在下,用H 2 O 2对一系列多加氧的查耳酮进行环氧化,以中等至高的光学收率得到了手性芳族加氧的环氧乙烷。路易斯酸催化的苯基甲的环氧化物官能团和吡喃酮杂环的随后形成,得到ringopening反式-和CIS在中度至高度对映体过量和产量-dihydroflavonols。