Prévost hydroxylation

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The Prévost hydroxylation (also: Prévost reaction) is a chemical reaction in which two hydroxyl groups can be added to alkenes under mild chemical conditions . In contrast to the Prévost-Woodward hydroxylation , in this reaction both hydroxyl groups of the diol are anti to each other. The reaction is named after Charles Prévost (1899–1983).

Gross equation of the Prévost hydroxylation

mechanism

In the first step, the alkene reacts with elemental iodine to form a cyclic iodonium ion. This is then opened by the silver benzoate and trans-1,2- iodocarboxylate is formed . After an intermolecular rearrangement, the iodine is split off and a cationic cyclic intermediate is formed. This is opened again by a second silver benzoate and the trans-1,2-dicarboxylate is formed. In the last step, the ester groups are hydrolyzed (see saponification ). Since the hydrolysis does not change the configuration of the molecule , the resulting hydroxyl groups remain anti to each other.

Mechanism of Prévost hydroxylation

literature

  • C. Prévost: Compt. Rend. 196 , 1129 (1933); CA 27 , 3195 (1933).
  • Michael B. Smith, Jerry March: March's Advanced Organic Chemistry. Reactions, Mechanisms, and Structure . 5th ed. Wiley-Interscience, New York 2001, pp. 1049-1050, ISBN 0-471-58589-0 .
  • Strategic Applications of Named Reactions in Organic Synthesis, László Kürti & Barbara Czakó, 2005, Elsevier Academic Press, 1st edition, ISBN 0-12-369483-3 .