An efficient and mild bismuth triflate-catalysed three-component Mannich-type reaction.

Thierry Ollevier1, Etienne Nadeau

  • 1Département de Chimie, Université Laval, Québec, Canada. thierry.ollevier@chm.ulaval.ca

Summary

A new catalytic method enables aldehydes and amines to react with silyl enolates, forming Mannich-type adducts. This efficient synthesis yields beta-amino ketones and esters in high amounts.

Related Concept Videos

Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride01:26

Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride

Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview01:07

Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview

In the presence of an aqueous base and a halogen, primary amides can lose the carbonyl (as carbon dioxide) and undergo rearrangement to form primary amines. This reaction, called the Hofmann rearrangement, can produce primary amines (aryl and alkyl) in high yields without contamination by secondary and tertiary amines.
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction01:22

Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction

The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction01:15

α-Bromination of Carboxylic Acids: Hell–Volhard–Zelinski Reaction

The method to achieve α-brominated carboxylic acids using a mixture of phosphorus tribromide and bromine is known as the Hell–Volhard–Zelinski reaction. The reaction is catalyzed by phosphorus tribromide, which can be used directly or produced in situ from red phosphorus and bromine. The mechanism comprises PBr3 catalyzed conversion of acid to acid bromide and hydrogen bromide. The acid bromide enolizes to its enol form in the presence of HBr. The nucleophilic enol attacks the bromine molecule...
Acid Halides to Ketones: Gilman Reagent01:14

Acid Halides to Ketones: Gilman Reagent

Lithium dialkyl cuprate, also known as Gilman reagents, selectively reduces acid halides to ketones. The acid chloride is treated with Gilman reagent at −78 °C in the presence of ether solution to produce a ketone in good yield.
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen double...
Acid Halides to Alcohols: Grignard Reaction01:15

Acid Halides to Alcohols: Grignard Reaction

Organomagnesium halides, commonly known as Grignard reagents, convert acid halides to tertiary alcohols. The reaction requires two equivalents of the Grignard reagent and proceeds via a ketone intermediate.
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...