Esters and Amides from ActivatedAlcohols using Manganese(IV) Dioxide: Tandem Oxidation Processes
作者:Richard J. Taylor、Jonathan S. Foot、Hisashi Kanno、Gerard M. Giblin
DOI:10.1055/s-2003-39163
日期:——
with sodium cyanide in THF-methanol or in methanol alone for the direct conversion of activated alcohols into methyl esters. Ethyl and isopropyl esters can also be prepared. Similarly, use of manganese(IV) dioxide and sodium cyanide in THF containing ammonia or primary amines can be used to convert alcohols into the corresponding amides. Several activated alcohols and one non-activated alcohol example
Photocatalyzed Triplet Sensitization of Oximes Using Visible Light Provides a Route to Nonclassical Beckmann Rearrangement Products
作者:Xiao Zhang、Tomislav Rovis
DOI:10.1021/jacs.1c10148
日期:2021.12.22
photoisomerization of oximes via visible-light-mediated energy transfer (EnT) catalysis. Facile access to (Z)-oximes provides opportunities to achieve regio- and chemoselectivity complementary to those of widely used transformations employing oxime starting materials. We show an enhanced one-pot protocol for photocatalyzed oxime isomerization and subsequent Beckmannrearrangement that enables novel reactivity with
feasible in many cases. The energy transfer (EnT) E/Z-photoisomerization might yield the Z-isomers. In this work, CBZ6 was proven to be an EnT photocatalyst for the E → Z-isomerization of C–C or C–N double bonds. The transformations of in situ generated Z-isomers of oximes and stilbenes consequently afforded the desired reversed Beckmannrearrangement products and phenanthrenes, respectively.
考虑到化学选择性的区域选择性, Z-异构体和E-异构体的反应通常是不同的。 Z-异构体的合成在许多情况下是不可行的。能量转移 (EnT) E / Z光异构化可能会产生Z异构体。在这项工作中, CBZ6被证明是一种用于 C-C 或 C-N 双键E → Z异构化的 EnT 光催化剂。原位生成的肟和茋的Z-异构体的转化因此分别提供了所需的反向贝克曼重排产物和菲。