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The Beckmann rearrangement scheme for acetophenone oxime under oxonium–acetic acid complex and hydronium–water complex. With the cyclohexanone-oxime, the relief of ring strain results in a third reaction mechanism, leading directly to the protonated caprolactam in a single concerted step without the intermediate formation of a π-complex or ...
In organic chemistry, an oxime is an organic compound belonging to the imines, with the general formula RR’C=N−OH, where R is an organic side-chain and R' may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted oximes form a closely related family of compounds.
Acetophenone is formed as a byproduct of the cumene process, the industrial route for the synthesis of phenol and acetone.In the Hock rearrangement of isopropylbenzene hydroperoxide, migration of a methyl group rather than the phenyl group gives acetophenone and methanol as a result of an alternate rearrangement of the intermediate:
The mechanism requires zinc and acetic acid as catalysts. It will proceed at room temperature. Because α-aminoketones self-condense very easily, they must be prepared in situ. The usual way of doing this is from the relevant oxime, via the Neber rearrangement. [5] [6]
Then, the enolate attacks the ester carbonyl to form a cyclic alkoxide. The cyclic intermediate is opened up to form a more stable phenolate, which is protonated during acidic work-up to give the desired product. The Baker-Venkataraman rearrangement mechanism. To complete the construction of the chromone or flavone core, cyclodehydration is ...
The scheme depicts the mechanism for the Leuckart reaction using formamide as the reducing agent. Formamide first nucleophilically attacks the carbonyl carbon. The oxygen is protonated by abstracting hydrogen from the nitrogen atom, subsequently forming a water molecule that leaves, forming N-formyl derivative, which is resonance stabilized. [3]
The reaction mechanism for the Johnson–Corey–Chaykovsky reaction consists of nucleophilic addition of the ylide to the carbonyl or imine group. A negative charge is transferred to the heteroatom and because the sulfonium cation is a good leaving group it gets expelled forming the ring.
Below, the reaction mechanism is shown with R 2 = H: Mukaiyama Aldol-MechanismusV7 en. In the cited example the Lewis acid TiCl 4 is used. First, the Lewis acid activates the aldehyde component followed by carbon-carbon bond formation between the enol silane and the activated aldehyde. With the loss of a chlorosilane the compound 1 is built.