Iridium complexes of chiral oxazoline-based P,N-ligands provedto be efficient catalysts for the enantioselective hydrogenationof 2-aryl- and 2-alkyl-4 H-chromenes.The best results were obtained with a ligand derived from threonine(ThrePHOX), which induced ee values of 95% to >99% inthe hydrogenation of 2-methyl-, 2-cyclohexyl- and various 2-aryl-substitutedchromenes.
手性恶唑啉基P,N-配体的铱配合物被证明是2-芳基-和2-烷基-4 H-色烯对映选择性加氢的有效催化剂。使用苏氨酸衍生的配体(ThrePHOX)获得了最好的结果。在 2-甲基-、2-环己基-和各种 2-芳基-取代的色烯的氢化中诱导 ee 值达到 95% 至 >99%。
Hypervalent Iodine Oxidation of Flavanones: A New Synthesis of Methyl 2-Aryl-2,3-dihydrobenzofuran-3-carboxylates by 1,2-Aryl Shift
作者:Om Prakash、Madan P. Tanwar
DOI:10.1246/bcsj.68.1168
日期:1995.4
Flavanones (1), on oxidation with (diacetoxyiodo)benzene-sulfuric acid (DIB–H2SO4) or (hydroxy)tosyloxy)iodo)benzene (HTIB) in trimethyl orthoformate, undergo facile ring contraction by 1,2-aryl shift, thereby yielding methyl 2-aryl-2,3-dihydrobenzofuran-3-carboxylates (4) as major products (40—80%). cis-3-Methoxyflavanones (5) and flavones (3) are the minor products formed in variable ratios.
Manganese(III) Acetate Mediated Oxidation of Flavanones: A Facile Synthesis of Flavones
作者:Om V. Singh、M. Muthukrishnan、Gopan Raj
DOI:10.1080/00397910500214490
日期:2005.10.1
Abstract Oxidation of flavanones (1a–o) with manganese(III) acetate by heating in acetic acid in presence of perchloric acid afforded exclusively flavones (2a–o) by dehydrogenation in almost quantitative yields.
First Vilsmeier-Haack Synthesis of Flavones using<i>bis</i>-(Trichloromethyl) Carbonate/Dimethylformamide
作者:W. K. Su、X. Y. Zhu、Z. H. Li
DOI:10.1080/00304940802710947
日期:2009.3.20
cyclodehydration of 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones. Many of these procedures use strong acids such as H2SO4, 5-6 HCl, 7 HBr or HI, 8 catalysts such as NaHSO4/SiO2, 9 H3PMo12O40·nH2O/SiO2, 10 H3PW12O40·nH2O/SiO2, 10 non-aqueous cation-exchange resin, 11 or supported trifluoromethanesulfonicacid. 12 All of these agents require high temperatures to complete the reaction. Other methods include
Mechanically Activated Solid-State Synthesis of Flavones by High-Speed Ball Milling
作者:Xingyi Zhu、Zhenhua Li、Qiangfeng Shu、Chenfeng Zhou、Weike Su
DOI:10.1080/00397910902898551
日期:2009.11.5
Abstract An efficient, mechanicallyactivated solid-state synthesis of flavones from 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones using high-speedballmilling is described. This method has notable advantages in terms of good yield, short reaction time, and neat conditions.