Baker-Venkataraman rearrangement

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The Baker-Venkataraman rearrangement is an intramolecular variant of the Allan-Robinson reaction . It is used for the synthesis of 1,3-di ketone substituted derivatives of phenol . This is based on an acylated phenol derivative. The reaction is named after its discoverers, the British chemist Wilson Baker (1900–2002) and K. Venkataraman (1901–1981).

Overview of the Baker-Venkataraman rearrangement

mechanism

In the first step , a base catalyzes the formation of an enolate . This attacks intramolecularly on the carbonyl group of the phenol ester . A cyclic alcoholate is formed in the process. This opens with the formation of a phenolate. In the last step, the phenolate is protonated by acidic work-up .

Mechanism of the Baker-Venkataraman rearrangement

use

The Baker-Venkataraman rearrangement is used as a key step in the formation of flavones and chromenes .

Individual evidence

  1. ↑ TS Wheeler: Flavones In: Organic Syntheses . 32, 1952, p. 72, doi : 10.15227 / orgsyn.032.0072 ; Coll. Vol. 4, 1963, p. 478 ( PDF ).
  2. ^ Wilson Baker: Molecular rearrangement of some o-acyloxyacetophenones and the mechanism of the production of 3-acylchromones. In: Journal of the Chemical Society (Resumed). 1933, pp. 1381-1389, doi : 10.1039 / JR9330001381 .
  3. ↑ Harbhajan S. Mahal, Krishnasami Venkataraman: Synthetical experiments in the chromone group. Part XIV. The action of sodamide on 1-acyloxy-2-acetonaphthones. In: Journal of the Chemical Society (Resumed). 1934, pp. 1767-1769, doi : 10.1039 / JR9340001767 .
  4. ↑ PK Jain, JK Makrandi, SK Grover: A Facile Baker-Venkataraman Synthesis of Flavones using Phase Transfer Catalysis. In: Synthesis '. 1982, No. 3, 1982, pp. 221-222, doi : 10.1055 / s-1982-29755 .
  5. ↑ Alexey V. Kalinin, Alcides JM da Silva, Claudio C. Lopes, Rosangela SC Lopes, Victor Snieckus: Directed ortho metalation - cross coupling links. Carbamoyl rendition of the baker-venkataraman rearrangement. Regiospecific route to substituted 4-hydroxycoumarins. In: Tetrahedron Letters . 39, No. 28, 1998, pp. 4995-4998, doi : 10.1016 / S0040-4039 (98) 00977-0 .

Web links

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