2,2-Dimethyl-5-(5-R-furfurylidene)-1,3-dioxane-4,6-diones. 3. Selective hydrogenation of the exocyclic double bond and three-dimensional structures of the reaction products
The Reaction of Meldrum's Acid and Its Derivatives with Conjugated Azoalkenes: A Convenient Route to 1-Amino-1<i>H</i>-pyrrol-2(3<i>H</i>)-ones
作者:Antonio Arcadi、Orazio A. Attanasi、Zhiyuan Liao、Franco Serra-Zanetti
DOI:10.1055/s-1994-25532
日期:——
The reaction of Meldrum's acid and its 5-substituted derivatives with conjugated azoalkenes in the presence of triethylamine produces, via 1,4-conjugate addition, corresponding hydrazones which undergo decarboxylative alcoholysis and simultaneous cyclization to give 3-unsubstituted and 3-monosubstituted 1-amino-1H-pyrrol-2-(3H)-ones respectively.
synthesis of a new class of densely functionalized β2,2-amino acidderivatives by reacting isoxazolidin-5-ones with para-quinone methides in the presence of chiral ammonium salt phase-transfer catalysts was developed. The reaction proceeds with exceptionally low catalyst loadings down to 20 ppm on gram scale and the utilization of the primary addition products towards further manipulations was demonstrated
C5‐disubstituted Meldrum's acid precursors were shown to be a useful platform for the synthesis of an array of 3‐alkylated dihydrocoumarins with up to 93:7 er, thanks to an enantioselective domino cyclization‐decarboxylative‐protonation reaction triggered by an unprecedented benzhydryl‐derived cupreine organocatalyst. This cyclization sequence was extended to an emerging organocatalytic decarboxylative‐chlorination
Meldrum's acid can be reductively alkylated with borane⋯dimethylamine complex and aldehydes or ketones; borane⋯trimethylamine was used with cyclohexanone.
Multi-catalysis cascade reactions based on the methoxycarbonylketene platform: diversity-oriented synthesis of functionalized non-symmetrical malonates for agrochemicals and pharmaceuticals
作者:Dhevalapally B. Ramachary、Chintalapudi Venkaiah、Y. Vijayendar Reddy、Mamillapalli Kishor
DOI:10.1039/b901652j
日期:——
In this paper we describe new multi-catalysis cascade (MCC) reactions for the one-pot synthesis of highly functionalized non-symmetrical malonates. These metal-free reactions are either five-step (olefination/hydrogenation/alkylation/ketenization/esterification) or six-step (olefination/hydrogenation/alkylation/ketenization/esterification/alkylation), and employ aldehydes/ketones, Meldrum's acid, 1,4-dihydropyridine/o-phenylenediamine, diazomethane, alcohols and active ethylene/acetylenes, and involve iminium-, self-, self-, self- and base-catalysis, respectively. Many of the products have direct application in agricultural and pharmaceutical chemistry.