10.1007/s00706-011-0618-z
The research presents the synthesis and stereochemistry of eleven novel dihydropyrrolo[3,4-c]pyrazole derivatives, which were obtained through the 1,3-dipolar cycloaddition reaction of chiral (1R)-N(1-phenylethyl)maleimide with C,N-aryl-substituted nitrilimines. The reaction yielded a regioisomeric mixture of cycloadducts, which were separable in some instances. The experiments involved the preparation of hydrazones and hydrazonyl chlorides from para-substituted aromatic aldehydes and hydrazines, followed by the cycloaddition reaction with the chiral maleimide in dry acetonitrile at room temperature. The structures and stereochemistry of the resulting cycloadducts were elucidated using infrared (IR) spectroscopy, proton and carbon-13 nuclear magnetic resonance (NMR), mass spectrometry, X-ray diffraction, and elemental analysis, providing comprehensive characterization of the novel compounds.
10.1016/j.tet.2012.11.011
The research focuses on the enantioselective Diels-Alder reaction of anthrone and maleimide, catalyzed by simple chiral tertiary amines with a special imide skeleton. The purpose of this study was to develop a new catalytic system that could achieve excellent yields and enantioselectivities in the construction of optically active unsaturated lactams, which are key intermediates for preparations of compounds with potential antipsoriatic and antiproliferative biological activities. The researchers successfully applied these amines, achieving yields up to 96% and enantioselectivities up to 95% ee.
10.1055/s-0034-1380404
The research aims to develop an efficient and environmentally friendly method for the synthesis of alkyl fumarate derivatives or 3-substituted succinimides using BF3·OEt2 as a catalyst. The study focuses on the regioselective 1,2-addition or 1,4-hetero-Michael addition of oxygen, sulfur, and nitrogen nucleophiles to maleimides, which are important building blocks in organic synthesis. The reaction system was found to have a wide substrate scope and yielded moderate to excellent results (up to 96%). The use of BF3·OEt2 as a catalyst was highlighted for its simplicity, efficiency, and tolerance of oxygen, offering a significant improvement over base-catalyzed methods.
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