Regio- and stereocontrol in the intramolecular nitrile oxide cycloaddition to 2-furylthiol- and 2-furylmethanethiol derivatives.
摘要:
A series of 2-furyl and 2-furylmethyl substituted nitrosulphides with a proper chain length were prepared and showed to undergo a totally regiocontrolled intramolecular furan-nitrile oxide cycloaddition to give cis-fused products in high yield. Insertion of a stereocenter on the cycloaddends did not allow satisfactory control of the absolute stereochemistry of the reaction. Enantiomerically enriched products (e.e. less-than-or-equal-to 95%) were obtained by a kinetic resolution process involving oxidation of the sulphide cycloadducts to the corresponding sulphoxides.
A series of 2-furyl and 2-furylmethyl substituted nitrosulphides with a proper chain length were prepared and showed to undergo a totally regiocontrolled intramolecular furan-nitrile oxide cycloaddition to give cis-fused products in high yield. Insertion of a stereocenter on the cycloaddends did not allow satisfactory control of the absolute stereochemistry of the reaction. Enantiomerically enriched products (e.e. less-than-or-equal-to 95%) were obtained by a kinetic resolution process involving oxidation of the sulphide cycloadducts to the corresponding sulphoxides.
Organocatalysis in Radical Chemistry. Enantioselective α-Oxyamination of Aldehydes
作者:Mukund P. Sibi、Masayuki Hasegawa
DOI:10.1021/ja069245n
日期:2007.4.1
We have developed an efficient radical α-oxyamination reaction using chiral organocatalysts. The reaction can be carried out with inexpensive SET reagents, and a reasonably broad substrate scope has been established. Good to high enantioselectivity for the α-oxygenated products are obtained using 20 mol % of the catalyst. The methodology reported in this work adds to the repertoire of asymmetric radical
我们开发了一种使用手性有机催化剂的高效自由基 α-氧胺化反应。该反应可以使用廉价的 SET 试剂进行,并且已经建立了相当广泛的底物范围。使用 20 mol% 的催化剂可以获得良好到高的 α-氧化产物的对映选择性。这项工作中报道的方法增加了可以使用有机催化剂进行的不对称自由基反应的全部内容。