catalytic methods for the oxidative furan-recyclizations remain scarcely investigated. Given this, we report a means of manganese-catalyzed oxidations of furan with low loading, achieving the Achmatowiczrearrangement in the presence of hydrogen peroxide as an environmentally benign oxidant under mild conditions with wide functional group compatibility.
herein an unprecedented highly efficient Guerbet‐type reaction at room temperature (catalytic TON up to >6000). This β‐alkylation of secondary methyl carbinols with primary alcohols has significant advantage of delivering higher‐order secondary alcohols in an economical, redox‐neutral fashion. In addition, the first enantioselective Guerbet reaction has also been achieved using a commercially available
benign cobaltouschloride efficiently accomplishes the catalytic β-alkylation of alcohols in air at 140 °C. At higher loadings of cobaltouschloride (1 mol%) in the presence of 2.5 mol% NaOtBu, there is a rapid formation of heterogeneous Co nanoparticles (NPs) which are apparently sensitive to air and result in poor yields (ca. 25%) of β-alkylated products. In contrast, performing the reaction in an
价格低廉、地球资源丰富且对环境无害的氯化钴可在 140 °C 的温度下有效地在空气中实现醇的催化 β-烷基化。在存在 2.5 mol% NaO t Bu 的情况下,在较高的氯化钴负载量 (1 mol%) 下,会快速形成对空气明显敏感的异质 Co 纳米颗粒 (NPs),导致产率低 ( ca. 25% ) 的 β-烷基化产物。相比之下,在其他相同条件下在氩气气氛中进行反应会导致更高的产率(约44%)。通过在 2.5 mol% NaO t存在下以较低 (0.01 mol%) CoCl 2负载运行可以延迟空气中的异质化和最终活性损失卜在 140 °C。在这些条件下,醇的催化 β-烷基化以高产率(高达 89%)和前所未有的周转率(约8900 年)进行。机理研究表明基于原位生成的醇分子 Co 配合物的催化剂的参与。标记研究为 C-H 活化参与氯化钴催化的 β-烷基化提供了关键证据,KIE 为 1.61
Visible-Light-Mediated Achmatowicz Rearrangement
作者:Matthew B. Plutschack、Peter H. Seeberger、Kerry Gilmore
DOI:10.1021/acs.orglett.6b03237
日期:2017.1.6
method to access highly reactive intermediates from cheap, readily available, and shelf-stable reagents to perform clean chemical transformations. Here, we report the first photoredox-catalyzed Achmatowicz reaction of furfuryl alcohol derivatives to produce functionalized dihydropyranones while only forming easily separable NaHSO4 as a byproduct. The water solubility of the byproduct facilitates direct
Two catalytic protocols for Achmatowicz rearrangement using cyclic diacyl peroxides as oxidants
作者:Congyin Wei、Rong Zhao、Zhihong Shen、Denghu Chang、Lei Shi
DOI:10.1039/c8ob01382a
日期:——
In situ generated bromonium-catalyzed and visible-light photocatalytic Achmatowiczrearrangements of furfuryl alcohols using cyclic diacyl peroxides as oxidants are described. Both protocols feature broad substrate scope, excellent functional group tolerance, and mild reaction conditions, affording the synthetically useful dihydropyranone derivatives in good yields.