DMF Dimethyl Acetal as Carbon Source for α-Methylation of Ketones: A Hydrogenation–Hydrogenolysis Strategy of Enaminones

Abstract

A novel heterogeneous catalytic hydrogenation-hydrogenolysis strategy has been developed for the α-methylation of ketones via enaminones using DMF dimethyl acetal as carbon source. This strategy provides a very convenient route to α-methylated ketones using a variety of ketones without any base or oxidant.

Synthesis of Quinazolinones, Imidazo[1,2‐c]quinazolines and Imidazo[4,5‐c]quinolines through Tandem Reductive Amination of Aryl Halides and Oxidative Amination of C(sp3)–H Bonds

“…Based on the results of our control experiments, and on literature reports, a proposed mechanism for the tandem reaction is shown in Scheme 3. Initially, copper-catalyzed reductive amination of 1a with sodium azide produces 2-(2-aminophenyl)-4,5-diphenyl-1H-imidazole (9). This is consistent with earlier reports in which sodium azide or TMSN 3 was used as an ammonia surrogate to prepare primary amines and nitrogen-containing heterocycles in a copper-catalyzed reductive amination reaction of aryl halides.…”

“…The most common methods for the synthesis of quinazolinones, and fused indolo-, benzimidazo-and imidazo-quinazolines and quinolines use aldehydes or aldehyde derivatives as the carbon source. [7] In the last few years, N,N-dimethylformamide (DMF), [8] dimethyl acetal, [9] N,N-dimethylacetamide (DMA), [10] and dimethyl sulfoxide (DMSO) [11] have been increasingly used as one-carbon sources in various organic transformations. On the other hand, the oxidative amination of C(sp 3 )-H bonds of inert hydrocarbons has become an attractive and vital tool for the construction of C-N bonds.…”

N‐Heterocyclic Carbene‐Catalyzed Mannich Reaction for the Synthesis of β‐Amino Ketones: N,N‐Dimethylformamide as Carbon Source

“…(4)]. We envisioned that the reaction proceeds with the coupling of acetophenone enol and the iminium ion generated from DMF to give an intermediate phenyl vinyl ketone with the elimination of N ‐methylformamide as reported in the literature ,. In order to prove this pathway, phenyl vinyl ketone was reacted with 2‐aminopyridine in DMF as solvent to give the desired β‐amino ketone within 2 h in excellent yield.…”

Recent Advances in Methylation: A Guide for Selecting Methylation Reagents

“…Gogoi et al. have devised a synthetic approach that comprises the condensation of ketones 12 with DMF‐DMA followed by the hydrogenation–hydrogenolysis of enaminones 14 , 15 to afford products 18 , 19 through the Pd/C‐catalyzed hydrogenation–hydrogenolysis of 16 and 17 , respectively . When the aromatic ring is substituted with an electron‐rich group, or there is an ortho substituent, the α‐methylated product 19 is the main product.…”