Sommelet-Hauser rearrangement

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The Sommelet – Hauser rearrangement , also known as Sommelett's rearrangement , is named after Marcel Sommelet and Charles R. Hauser (1900-1970). In organic chemistry, it is one of the rearrangement reactions . Here are quaternary benzyl ammonium salts in tertiary rearranged amines: The rearrangement takes place under the influence of sodium or other alkali metal. Starting from a trialkylbenzylammonium salt (e.g. trimethylbenzylammonium salt ), the Sommelet – Hauser rearrangement gives an N -dialkylbenzylamine with an alkyl substituent (e.g. methyl substituent ) in the ortho position of the aromatic :

Reaction scheme for the Sommelet-Hauser rearrangement

The Stevens rearrangement is a competitive reaction to the Sommelet – Hauser rearrangement.

Reaction mechanism

One of the hydrogen atoms on the benzyl carbon atom can be split off under basic conditions, resulting in an ylide 1 . 1 is in equilibrium with the (less favored!) Isomeric ylide 2 , which now rearranges ([2,3] - sigmatropic rearrangement ) to form an ortho- quinoid, which tautomerizes with rearomatization to the ortho -substituted amine 3 .

Reaction mechanism of the Sommelet-Hauser rearrangement

Application examples

The Sommelet – Hauser rearrangement is widely applicable and was used in the total synthesis of the antibiotic natural substance streptonigrin.

Individual evidence

  1. ↑ M. Sommelet, Compt. Rend. 205, 56 (1937).
  2. ↑ Simon W. Kantor, Charles R. Hauser: Rearrangements of Benzyltrimethylammonium Ion and Related Quaternary Ammonium Ions by Sodium Amide Involving Migration into the Ring. In: J. Am. Chem. Soc. 1951, 73 (9), pp. 4122-4131 ( doi : 10.1021 / ja01153a022 ).
  3. ↑ Michael B. Smith: March's advanced organic chemistry. 7th edition. John Wiley & Sons, 2013, ISBN 978-0-470-46259-1 , pp. 798-799.
  4. ^ Ernest L. Eliel, Samuel H. Wilen: Stereochemistry of Organic Compounds. John Wiles & Sons, 1994, ISBN 0-471-05446-1 , pp. 266-267.
  5. ↑ a b László Kürti , Barbara Czakó: Strategic Applications of Named Reactions in Organic Synthesis: Background and Detailed Mechanisms. Elsevier Academic Press, 2005, ISBN 0-12-429785-4 , pp. 422-423.
  6. ^ VK Ahluwalia, RK Parashar: Organic Reaction Mechanisms . Alpha Science International, Harrow, UK 2005. Print.