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。
Brønsted Acid-Promoted Cyclodimerization of Indolyl Ketones: Construction of Indole Fused-Oxabicyclo[3.3.1]nonane and -Cyclooctatetraene Ring Systems
A Brønsted acid-promoted cyclodimerization of C(3)-, C(2)-, or N(1)-substituted indole ketone derivatives is described. A wide range of structurally diverse bisindole fused-9-oxabicyclo[3.3.1]nonane and bisindole fused-cyclooctatetraene (COT) derivatives can be prepared in good to high yields with high efficiency.
Carbon–carbon double bonds in α,β-unsaturated nitro compounds are reduced smoothly into the corresponding nitro alkanes by a model of NAD(P)H in benzene in the presence of silica gel. Other functional groups are inert under the reaction conditions.
A Highly Chemoselective Reduction of Conjugated Nitro Olefins with Hantzsch Ester in the Presence of Silica Gel
作者:Masayuki Fujii
DOI:10.1246/bcsj.61.4029
日期:1988.11
An effective system to reduce conjugated nitro olefins into the corresponding nitroalkanes is described. The system composed of Hantzsch ester (HEH) and silica gel in benzene exerts high yield and excellent chemoselectivity under almost neutral conditions. Facile applications of the system to the syntheses of natural products are also described.