Organocatalytic Biomimetic Reduction of Conjugated Nitroalkenes
作者:Peter Schreiner、Zhiguo Zhang
DOI:10.1055/s-2007-983805
日期:2007.8
A thiourea-catalyzed biomimetic reduction of conjugatednitroalkenes has been developed. Various aromatic and aliphatic conjugatednitroalkenes can be reduced to give the respective nitroalkanes with good yields under mild conditions. This protocol is not only practical, but may also provide insight into the mechanisms of redox transformations in biological systems.
Weak Lewis acid for high nucleophilicity: Hydridoborate derived from B(2,6‐F2C6H3)3 shows significant hydride character. Solid‐state and solution structure analysis revealed a dihydrogen‐bonded aggregate. The new frustratedLewispair was applied in the hydrogenation of nitroolefins and acrylates (see scheme; EWG=electron‐withdrawing group). The decreased Lewis acidity provides higher reactivity and
弱路易斯酸,具有高亲核性:衍生自B(2,6-F 2 C 6 H 3)3的氢硼酸盐显示出显着的氢化物特征。固态和溶液结构分析表明,存在氢键结合的聚集体。新的受阻的路易斯对用于硝基烯烃和丙烯酸酯的氢化反应(参见方案; EWG =吸电子基团)。降低的路易斯酸度可提供更高的反应性和官能团耐受性。
Asymmetric Organocatalytic Sequential Reaction of Structurally Complex Cyclic Hemiacetals and Functionalized Nitro-olefins To Synthesize Diverse Heterocycles
作者:Jun-Ping Pei、Ying-Han Chen、Yan-Kai Liu
DOI:10.1021/acs.orglett.8b01386
日期:2018.6.15
Structurally complex cyclic hemiacetals bearing a racemic tetrasubstituted stereocenter have been prepared in a concise manner and were successfully used in an organocatalytic enantioselective sequence to react with functionalized nitro-olefins, providing bicyclic acetal-containing compounds as two separable epimers with excellent stereoselectivity. The reaction showed broad substrate scope, with respect
Cascade Formation of Isoxazoles: Facile Base-Mediated Rearrangement of Substituted Oxetanes
作者:Johannes A. Burkhard、Boris H. Tchitchanov、Erick M. Carreira
DOI:10.1002/anie.201100260
日期:2011.5.27
Give me five! Nitro compounds and oxetan‐3‐one react through an intriguing cascade sequence to give isoxazole‐4‐carbaldehydes using inexpensive reagents in a one‐pot procedure (see scheme; Ms=methanesulfonyl). A variety of 3‐substitutedisoxazole‐4‐carbaldehydes were obtained in high overall yields.
击个掌!硝基化合物和oxetan-3-one通过一个有趣的级联序列反应,使用便宜的试剂在单锅法中制得异恶唑4-甲醛(见方案; Ms =甲磺酰基)。以高总收率获得了各种3-取代的异恶唑-4-甲醛。
Enantioselective Conjugate Addition of Nitroalkanes to Vinyl Sulfone: An Organocatalytic Access to Chiral Amines
作者:Qiang Zhu、Yixin Lu
DOI:10.1021/ol9003349
日期:2009.4.16
Organocatalytic asymmetric conjugate addition of nitroalkanes to vinyl sulfone mediated by cinchona alkaloid-derived thiourea catalyst afforded the desired Michael product with good enantioselectivity. The described method, in combination with ready desulfonation, represents a novel approach to access α-alkylated chiral amines.