Heron rearrangement

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The Heron rearrangement is a name reaction from the field of organic chemistry , which was first presented to the public in 1994 by the chemist Stephen A. Glover at the second Heron Island Conference on Reactive Intermediates and Unusual Molecule in Australia. Hence the name Heron rearrangement comes from. Chemically it is a reaction of an amide with two substituents with heteroatoms on the nitrogen atom to an ester and a 1,1- diimine . The main product is the ester.

Overview

An amide substituted on the nitrogen atom by two heteroatoms, here substituted by a bromine atom and an alkoxy group , is reacted with an amine to form an ester and a 1,1-diimine.

R 1 , R 2 , R 3 , R 4 = organyl radical

A rearrangement of the alcoholate group from the nitrogen atom to the carbonyl carbon atom and an S N 2 reaction take place.

Instead of a N alkoxy N -bromoamide also may N alkoxy N -chloramid be used as a starting material. The use of an N- acyloxy- N -alkoxyamide instead of an N -alkoxy- N -halogenamide is also treated in the literature under the term Heron rearrangement.

Reaction mechanism

The following illustration describes a proposal for the reaction mechanism:

R 1 , R 2 , R 3 , R 4 = organyl radical

First, an S N 2 reaction takes place between an amide 1 and an amine. Then the leaving group of the S N 2 reaction, here a bromide anion, deprotonates the proton formed on the amine nitrogen atom. This is how dinitrogen compound 2 is created . The rearrangement of the alkoxy group ( OR 1 ) from the nitrogen atom to the carbonyl carbon atom then takes place. After splitting off a diimine disubstituted in the 1-position, the ester 3 is formed . In addition, every two molecules of the diimine can be converted into one molecule of a 1,1-diimine 4 .

Individual evidence

  1. ↑ Stephen A. Glover, Gerard P. Hammond, Antonio M. Bonin: A Comparison of the Reactivity and Mutagenicity of N- (Benzoyloxy) -N- (benzyloxy) benzamides . In: The Journal of Organic Chemistry . tape 63 , no. December 26 , 1998, pp. 9684-9689 , doi : 10.1021 / jo980863z .
  2. ↑ Stephen A. Glover, Guoning Mo: Hindered ester formation by SN2 azidation of N-acetoxy-N-alkoxyamides and N-alkoxy-N-chloroamides — novel application of HERON rearrangements . In: Journal of the Chemical Society, Perkin Transactions 2 . No. 10 , October 2002, p. 1728-1739 , doi : 10.1039 / B111250N .
  3. ↑ Stephen A. Glover, Arvi Rauk: Conformational Stereochemistry of the HERON Amide, N-Methoxy-N-dimethylaminoformamide: A Theoretical Study . In: The Journal of Organic Chemistry . tape 64 , no. 7 , April 1999, p. 2340-2345 , doi : 10.1021 / jo982048p .
  4. ↑ a b c d e f 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 , p 1392-1393.
  5. ↑ Stephen A. Glover: Anomeric amides - Structure, properties and reactivity . In: Tetrahedron . tape 54 , no. 26 , June 25, 1998, pp. 7229-7271 , doi : 10.1016 / S0040-4020 (98) 00197-5 .
  6. ^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals. 14th Edition (Merck & Co., Inc.), Whitehouse Station, NJ, USA, 2006, ISBN 978-0-911910-00-1 , p. ONR-43.