Monoallylation and monoalkylation of diketones and β-keto esters with allylic and benzylic alcohols catalysed by [Cp*Co(CH3CN)3][SbF6]2 (I) are reported. The method does not require any additive and affords regioselective products. The mechanistic investigations were done by in situ 1H NMR spectroscopy as well as control experiments. It has been shown that reactions proceed via η3-allyl complex formation or
报道了[Cp*Co(CH 3 CN) 3 ][SbF 6 ] 2 ( I )催化的二酮和β-酮酯与烯丙醇和苄醇的单烯丙基化和单烷基化。该方法不需要任何添加剂并提供区域选择性产物。通过原位1 H NMR 光谱以及对照实验进行了机理研究。已表明反应通过形成 η 3 -烯丙基络合物或烯丙基醚中间体进行。烷基化仅通过醚中间体发生。所得烯丙基化和烷基化产物已用于合成十一种新的三取代吡唑和一种吡唑啉酮。
作者:Tuong Anh To、Chao Pei、Rene M. Koenigs、Thanh Vinh Nguyen
DOI:10.1002/anie.202117366
日期:2022.3.21
H-bonding network: Hexafluoroisopropanol (HFIP) can act as a hydrogen-bond donor to enhance the catalytic efficiency of simple Brønsted acid catalysts in carbonyl-olefin metathesis reactions by stabilization of all transition states and intermediates along the reaction pathway.
Both dihydrofuran and dihydropyran derivatives are obtained performing iodoenolcyclization of 2-alkenyl-1,3-dicarbonyl compounds having a highly substituted double bond. The regiochemistry is greatly dependent on the nature of carbonyl groups.
derivatives were obtained by a simple one-step procedure involving an easy epoxidation of 2-alkenyl-1,3-dicarbonyl compounds by dimethyldioxirane prepared in situ and a subsequent cyclisationunder the same basic reaction conditions.
A highly efficient and environmentally friendly method for catalytic benzylation/allylation of 1,3-dicarbonyl compounds with alcohols has been developed by using Yb(OTf)(3) as a catalyst. The reactions proceed smoothly to give the desired products in moderate to excellent yields, mostly at room temperature. The catalyst can be recovered and reused at least six times without visible loss of catalytic activity for such reactions. (c) 2007 Elsevier Ltd. All rights reserved.