A Study on the Conformation−Anomeric Effect−Stereoselectivity Relationship in Anomeric Radical Reactions, Using Conformationally Restricted Glucose Derivatives as Substrates
that, since the stereoselectivity of anomericradical reactions is significantly influenced by the kinetic anomeric effect, which can be controlled by restricting the conformation of the radical intermediate, the proper conformational restriction of the pyranose ring of the substrates would therefore make highly alpha- and beta-stereoselective anomericradical reactions possible. This theory was based
Catalytic asymmetric epoxidation of alkenes with arabinose-derived uloses
作者:Tony K.M Shing、Yiu C Leung、Kwan W Yeung
DOI:10.1016/s0040-4020(03)00145-5
日期:2003.3
Four l-erythro-2-uloses were readily prepared from l-arabinose via a reaction sequenceinvolving Fischer glycosidation, acetalization and oxidation. Bulky steric sensors at the anomeric center could enhance the stereoselectivity of the dioxirane epoxidation and one of the uloses performed with good enantioselectivity towards trans-stilbene (up to 90% ee). However, the catalysts decomposed during the
Arabinose-Derived Ketones as Catalysts for Asymmetric Epoxidation of Alkenes
作者:Tony K. M. Shing、Gulice Y. C. Leung、To Luk
DOI:10.1021/jo050928f
日期:2005.9.1
Readily available arabinose-derived ketones, containing a tunable butane-2,3-diacetal as the steric blocker, displayed increasing enantioselectivity (up to 90% ee) with the size of the acetal alkyl group in catalytic asymmetricepoxidation of trans-disubstituted and trisubstituted alkenes. The stereochemical communication between our ketonecatalysts and the alkene substrates is mainly due to steric
Highly α- and β-Selective Radical<i> C</i>-Glycosylation Reactions Using a Controlling Anomeric Effect Based on the Conformational Restriction Strategy. A Study on the Conformation−Anomeric Effect− Stereoselectivity Relationship in Anomeric Radical Reactions
作者:Hiroshi Abe、Satoshi Shuto、Akira Matsuda
DOI:10.1021/ja011321t
日期:2001.12.1
stereoselectivity of anomeric radical reactions was significantly influenced by the anomericeffect, which can be controlled by restricting the conformation of the radical intermediate, the proper conformational restriction of the pyranose ring of the substrates would therefore make highly alpha- and beta-stereoselective anomeric radical reactions possible. Thus, the conformationally restricted 1-phenylseleno-D-xylose
Inhibitor Ionization as a Determinant of Binding to 3-Dehydroquinate Synthase
作者:Feng Tian、Jean-Luc Montchamp、J. W. Frost
DOI:10.1021/jo960709h
日期:1996.1.1
phosphorylmethyl, phosphonoethyl, and phosphonomethyl groups in carbocyclic inhibitors of DHQ synthase. All but one of the carbocyclic inhibitors were synthesized via intermediacy of a 2,3-butane bisacetal-protected 3-dehydroquinic acid. Carbaphosphinate (K(i) = 20 x 10(-)(6) M) was a modest competitive inhibitor of DHQ synthase, while carbaacetate was a linear mixed-type inhibitor (K(i) = 3 x 10(-)(6) M, K(i)'
在DHQ合酶的碳环抑制剂中,膦酰基甲基和羧甲基一元酸与琥珀酰基,丙二酰基醚,丙二酰基和羟基丙二酰基二酸一起被磷酰基甲基,膦酰基乙基和膦酰基甲基取代。除一种碳环抑制剂外,所有化合物均通过2,3-丁烷双缩醛保护的3-脱氢奎尼酸的中间体合成。氨基膦酸酯(K(i)= 20 x 10(-)(6)M)是DHQ合酶的中等竞争性抑制剂,而氨基甲酸酯则是线性混合型抑制剂(K(i)= 3 x 10(-)(6) )M,K(i)'= 20 x 10(-)(6)M)。氨基甲酸酯(K(i)= 5 x 10(-)(6)M),氨基甲酸酯醚(K(i)= 7 x 10(-)(6)M),氨基甲酸酯(K(i)= 0.7 x 10( -)(6)M)和氨基甲酸丙二酸酯(K(i)= 0.3 x 10(-)(6)M)均为竞争性抑制剂。氨基甲酸酯是唯一未被DHQ合酶氧化的抑制剂。