Bodroux amide synthesis

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The Bodroux amide synthesis or Bodroux reaction is a name reaction in organic chemistry . It was published in 1904 by Fernand Bodroux (1873–1968). With the help of this reaction, substituted amides can be prepared from aromatic or aliphatic esters (R = alkyl radical , aryl radical ) and an aminomagnesium halide (R 1 = H, alkyl radical, aryl radical; R = alkyl radical, aryl radical):

Bodroux Amid overview version 1a.svg

The advantage of this reaction over alternative aminolysis is that it does not require high temperature or high pressure. Aminomagnesium halides can be produced by working up a primary or secondary amine with a Grignard compound at room temperature. It is also worth mentioning that the magnesium can be replaced by alkali metals , aluminum , tin or titanium , as well as the bromine used here by chlorine or iodine . This makes the Bodroux amide synthesis an important reaction, especially from an economic point of view.
The disadvantage compared to the alternative aminolysis is the formation of stoichiometric amounts of inorganic salts, e.g. B. Magnesium Salts. The atom economy of the Bodroux amide synthesis is therefore less favorable than aminolysis.

mechanism

The mechanism is shown here using magnesium bromide as an example. This mechanism is the same as the reaction of a Grignard compound with an ester.

Bodroux Amid Mecha Version 5.svg

First, an ester 1 (R = alkyl radical , aryl radical ) is mixed with a magnesium bromoamine. By rearrangement of electron pairs, the organyl magnesium bromide (R 1 = H, alkyl radical, aryl radical; R = alkyl radical, aryl radical) is attached to the oxygen atom and the nitrogen of the amine to the carbon atom of the carbonyl group. This gives the amine 2 . An intramolecular attack of the alkoxy group on the magnesium bromide now takes place. A magnesium salt separates out and the desired amide 3 is formed .

Modifications

The Bodroux amide synthesis has a number of modifications.

  • One of these modifications is the reaction of esters and lithium aluminum amides [LiAl (NH 2 ) 4 ]. It runs in diethyl ether already at 25  ° C . Due to these low temperatures, it is very energy-efficient and therefore very attractive economically.
  • Another modification is the reaction of a carboxylate with an amine and a Grignard compound . This modification is shown below using an example:
Example Bodroux Amid Version 2.svg

In this modification, a carboxymagnesium bromide 5 is first generated from propionic acid ( 4 ) with a Grignard compound . The desired N -ethylpropionic acid amide ( 6 ) is then obtained by adding ethylamine .

See also

Individual evidence

  1. ↑ MF Bodroux: Nouvelle methode de preparation des anilides . In: Comptes Rendus . tape 138 , 1904, pp. 1427-1429 .
  2. ↑ Bodroux synthesis. Retrieved June 9, 2013 .
  3. ↑ a b A. Solladie-Cavallo, M. Bencheqroun: Inexpensive reagents for the synthesis of amides from esters and for regioselective opening of epoxides . In: The Journal of Organic Chemistry . tape 57 , no. 22 , 1992, pp. 5831-5834 , doi : 10.1021 / jo00048a011 .
  4. ↑ a b c d Z. Wang (Ed.): Comprehensive Organic Name Reactions and Reagents, 3 Volume Set . John Wiley & Sons, Hoboken, New Jersey 2009, ISBN 978-0-471-70450-8 , pp. 445-446.
  5. ^ A b C. Aubert, C. Huard-Perrio, MC Lasne: Rapid synthesis of aliphatic amides by reaction of carboxylic acids, Grignard reagent and amines: application to the preparation of [11C] amides . In: Journal of the Chemical Society . tape 19 , 1997, pp. 2837-2842 , doi : 10.1039 / A702897K .