Visible-Light-Promoted Redox-Neutral Cyclopropanation Reactions of α-Substituted Vinylphosphonates and Other Michael Acceptors with Chloromethyl Silicate as Methylene Transfer Reagent
with chloromethyl silicate as a methylene transfer reagent has been accomplished via visible‐light‐mediated redox‐neutral catalysis. This method features broad functional group tolerance and mild conditions. In addition to α‐substituted vinylphosphonates, a range of Michael acceptors including α,β‐unsaturated acrylate, ketone, amide and sulfone are suitable substrates for this photocatalytic cyclopropanation
Intermediates in the asymmetric hydrogenation of unsaturated carboxylic acid derivatives
作者:John M. Brown、David Parker
DOI:10.1039/c39800000342
日期:——
Unsaturatedcarboxylicacids form several types of rhodium biphosphine complex which may affect the course of asymmetric hydrogenation reactions.
不饱和羧酸形成几种类型的铑双膦配合物,这可能会影响不对称氢化反应的进程。
Selective α‐Monomethylation by an Amine‐Borane/
<i>N</i>
,
<i>N</i>
‐Dimethylformamide System as the Methyl Source
作者:Hui‐Min Xia、Feng‐Lian Zhang、Tian Ye、Yi‐Feng Wang
DOI:10.1002/anie.201804794
日期:2018.9.3
A new and practical α‐monomethylation strategy using an amine‐borane/N,N‐dimethylformamide (R3N‐BH3/DMF) system as the methyl source was developed. This protocol has been found to be effective in the α‐monomethylation of arylacetonitriles and arylacetamides. Mechanistic studies revealed that the formyl group of DMF delivered the carbon and one hydrogen atoms of the methyl group, and R3N‐BH3 donated
a new desulfurative method for generating primary, secondary, and tertiary alkyl radicals through visible‐light photoredoxcatalysis. A process that involves the generation of N‐centered radicalsfrom sulfinamide intermediates, followed by subsequent fragmentation, is critical to forming the corresponding alkyl radical species. This strategy has been successfully applied to conjugate addition reactions
Alkenyl chlorides and bromides are converted into tertiary enamides by treatment with a carbamoylsilane in toluene at 110 degrees C in the presence of phosphine-palladium(0) catalysts. [reaction: see text]