DMF as Carbon Source: Rh-Catalyzed α-Methylation of Ketones
摘要:
An unprecedented Rh-catalyzed direct methylation of ketones with N,N'-dimethylformamide (DMF) is disclosed. The reaction shows a broad substrate scope, tolerating both aryl and alkyl ketones with various substituents. Mechanistic studies suggest that DMF delivers a methylene fragment followed by a hydride in the methylation process.
Chemoselective synthesis of ketones and ketimines by addition of organometallic reagents to secondary amides
作者:William S. Bechara、Guillaume Pelletier、André B. Charette
DOI:10.1038/nchem.1268
日期:2012.3
is of great importance, as this motif serves as a synthetic handle for the elaboration of numerous organic functionalities. In this context, we report a general and chemoselective method based on an activation/addition sequence on secondaryamides allowing the controlled isolation of structurally diverse ketones and ketimines. The generation of a highly electrophilic imidoyl triflate intermediate was
Conversion of Aldehydes to Branched or Linear Ketones via Regiodivergent Rhodium-Catalyzed Vinyl Bromide Reductive Coupling–Redox Isomerization Mediated by Formate
作者:Robert A. Swyka、William G. Shuler、Brian J. Spinello、Wandi Zhang、Chunling Lan、Michael J. Krische
DOI:10.1021/jacs.9b03113
日期:2019.5.1
coupling-redox isomerization to form branched ketones. Use of the less strongly coordinating ligand, PPh3, promotes vinyl- to allylrhodium isomerization en route to linear ketones. This method bypasses the 3-step sequence often used to convert aldehydes to ketones involving the addition of pre-metalated reagents to Weinreb or morpholine amides.
Palladium-catalyzed arylation of vinylic acetates. Phosphine ligand influenced regioselectivity
作者:Mickaël Jean、Jacques Renault、Pierre van de Weghe
DOI:10.1016/j.tetlet.2009.09.048
日期:2009.11
A palladium-catalyzed coupling reaction of aryl bromides with vinylic acetates in the presence of tributyltin methoxide has been described. The α-arylation aldehyde product and the aryl ketone were obtained in the presence of P(t-Bu)3 and P(o-Tol)3, respectively.
A direct transformation of secondary amides into α‐branched ketones with enamines as soft alkylation reagents was developed. In this reaction, enamines serve as surrogates of alkyl carbanions, rather than the conventional enolates equivalents in the Stork's reactions, which allowed for the easy introduction of alkyl groups with electrophilic functional groups. In the presence of 4 Å molecular sieves
zed carbonylations involved either toxic carbon monoxide (CO) gas as carbonylating agent or functional-group-assisted ortho sp2 C–H activation (i.e., ortho acylation) or carbonylation by activation of the carbonyl group (i.e., via the formation of enamines). Contradicting these methods, here we describe an environmentally benign process, [Pd]-catalyzed direct carbonylation starting from simple and