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What is Prévost Reaction?
Prévost Reaction is two-step organic transformation, treatment of styrene with silver benzoate and iodine in dry benzene as solvent deliver the dibenzoate ester of the corresponding glycol. after hydrolysis leads the 1,2-diol (trans-1,2-diols), and it is referred to as the Prévost reaction.
Acyclic and cyclic alkenes are good substrates. Commonly used reagent is silver benzoate (R=Ph), silver carboxylates or thallium(I)acetate. When isolated and conjugated double bonds are both present in the same substrate, the usual dihydroxylation takes place on the isolated double bond prefer.
![Prévost Reaction image |
prevost woodward reaction](https://chemistry-reaction.com/wp-content/uploads/2022/06/image-4.png)
Prévost Reaction Mechanism:
The first step alkene reacts with iodine to form the cyclic iodonium ion.
Next, the iodonium ion is stereospecifically opened by the silver carboxylate to form the corresponding trans-1,2-iodo carboxylate.
The iodine is displaced intramolecularly by the carbonyl group of the carboxylate (anchimeric assistance) to form a cyclic cationic intermediate.
In the absence of water, this cation is opened with the inversion of configuration by the second equivalent of silver carboxylate to afford the trans-1,2-dicarboxylate which further convert in 1-2 diol.
![Prévost Reaction Mechanism |
prevost woodward reaction mechanism](https://chemistry-reaction.com/wp-content/uploads/2022/06/image-5.png)
Related reaction:
Reference:
- Charles Prévost (1933). “Sur un complexe iodo-argento-benzoïque et son application à l’oxydation des combinaisons éthyléniques en α-glycols”. Comptes rendus. 196: 1129.
- Briggs, L. H., Cain, B. F., Davis, B. R. Novel Prevost reaction. Tetrahedron Letters 1960, 9-11.
My name is Pradip Sanjay W. I’m an organic chemist originally from Maharashtra, India. I have qualified UGC NET-JRF, GATE in chemical sciences and MH-SET exam for assistant professor. I’m currently pursuing my Ph.D. in organic chemistry at the Indian Institute of Technology Hyderabad, India.