The acid mediated reaction between active methylenes and benzhydrylalcohols, or their derivatives, is reported. Ethyl acetoacetate, acetylacetone, and N,N-dibenzyl-malonamic acid methyl ester are benzhydrylated in quantitative yields in the presence of molar amounts of BF 3 .OEt 2 in CH 2 Cl 2 at r.t. TMSOTf and H 2 SO 4 appear to be equally efficient. Use of benzhydryl acetate in place of the starting
报道了活性亚甲基和二苯甲醇或其衍生物之间的酸介导反应。在室温下 CH 2 Cl 2 中存在摩尔量的 BF 3 .OEt 2 时,乙酰乙酸乙酯、乙酰丙酮和 N,N-二苄基-丙二酸甲酯以定量产率二苯甲基化。 TMSOTf 和 H 2 SO 4 似乎是相同的高效的。使用乙酸二苯甲酯代替起始游离醇可以将路易斯酸降低到催化量。介绍了这种几乎没有研究的 CC 键形成的一般机制。由于醇相对于卤化物更容易获得,该方法可以与更经典的基于卤化物的碱性条件进行比较。
Casadei, Maria Antonietta; Cesa, Stefania; Inesi, Achille, Journal of Chemical Research, Miniprint, 1995, # 5, p. 1064 - 1079
作者:Casadei, Maria Antonietta、Cesa, Stefania、Inesi, Achille、Moracci, Franco Micheletti
DOI:——
日期:——
Substituted aryl malonamates as new serine β-lactamase substrates: Structure–activity studies
A series of substituted aryl malonamates have been prepared. These compounds are analogues of aryl phenaceturates where the amido side chain has been replaced by a retro-amide. Like the phenaceturates, these compounds are substrates of typical class A and class C beta-lactamases, particularly of the latter, and of soluble DD-peptidases. The effect of substituents alpha to the ester carbonyl group on turnover by these enzymes is similar to that in the phenaceturates. On the other hand, N-alkylation of the side chain amide of malonamates, but not of phenaceturates, retains the susceptibility of the compounds to hydrolysis by beta-lactamases. This reactivity is not enhanced, however, by bridging the amide nitrogen and C alpha atoms. A phosphonate analogue of the malonamates was found to be an irreversible inhibitor of the beta-lactamases. These results, therefore, provide further evidence for the covalent access of compounds bearing retroamide side chains to the active sites of beta-lactam-recognizing enzymes. (C) 2009 Elsevier Ltd. All rights reserved.
Palladium Catalysis in the Intramolecular Carbene C-H Insertion of α-Diazo-α-(methoxycarbonyl)acetamides to Form β-Lactams
The intramolecular carbene C–H insertion of α-diazo-α(methoxycarbonyl)acetamides leading to β-lactams is effectively catalyzed by palladiumcomplexes. It is found that whereas Pd(0)catalysts typically produce mixtures of β-lactams together with Buchner-type reaction products, the use of Pd(II)-catalysts results in highly chemoselective transformations. According to DFT calculations, this insertion reaction