Oxime rearrangement

The synthesis of 4-aza triterpenic derivative 362 (ring A modification) made use of the oxime rearrangement to promote the lactam formation (equation 141). Again, only one isomer of the product was observed. 

Beckmann rearrangement of 6-endo-chlorocamphor oxime (Vol. 7, p. 43) yields (220) and the cis- and frans-ring-fused (221), and camphor oxime rearranges with hydrazoic acid in polyphosphoric acid to yield (222). ... 

The benzenesulfonate of cycloheptanone oxime rearranges readily at room temperature to give the very electrophilic O- benzenesulfonate (7), which reacts with pyridine to give the salt (8) (67CB3024). Treatment of (8) with water gives (2), and with H2S the thione (9) is produced (58CB972). The reaction of aluminum alkyls with cycloheptanone oxime mesylate provides a direct route to 2-alkyl-substituted octahydroazocines (81JA7368). 

This oxime rearranges under acidic conditions to a seven-mernbered cyclic amide icaprolactam, that is the monomer used in making one of the must widely used types of nylon, namely nylon-6. A more specialized polyamide, nylon-T 2. is made in a similar way from cyclododecane (5.82) this polymer finds applications in coating metals and in making plastic components for motor cars. 

Oximes rearrange when heated with a strong acid, and this reaction provides a useful synthesis of amides ... 

Beckmann rearrangement, The p-toluenesulfonates of an oxime rearrange to amides in 45-90% yield when stirred at room temperature with Si02. 

The second route to 2,4-disubstituted adamantanes involves a 7r-route ring closure of substituted bicyclo[3.3.1]nonenes. Thus, lactone 85 28S) rearranges in 50 % sulfuric acid to 4-hydroxy-2-adamantanone (86) via the acylium ion 87 278>. Adamantanone oxime rearranges in 96 % sulfuric acid to 86 (mixture of isomers) in an analogous manner 109h Similarly, the Schmidt reaction of... 

Nitrofluorenone oxime rearranges to a single amide, 2-nitro-phenanthridone, in a mixture of phosphoryl chloride and phosphorus pentachloride. The same reagents convert 2-nitrofluorenone oxime (of apparent stereochemical purity) into a mixture of 3- and 8-nitrophenanthridone,97 though only the first product is formed in... 

Other types of allylic amination reactions include a variety of indirect approaches such as reduction of a,P-unsaturated imines and oximes, rearrangement of aziridines, and elimination of water from vicinal amino alcohols. However, these reactions will not be considered in this chapter [2]. 

Figure 26 Proposed mechanism for the S-1 catalyzed oxime rearrangement.

Simunic-Meznaric, V., Mihalic, Z., Vancik, H. Oxime rearrangements ab initio calculations and reactions in the solid state. J. Chem. Soc., Perkin Trans. 2 2002, 2154-2158. 

In the case of 4-oestrene-3,17-dione, protection of the 3-carbonyl group as its enol ether and subsequent oximation, rearrangement and deprotection gives the lactam with a functionality at C-3 which allows further elaboration to a neuromuscular blocker (R. J. Marshall et al.y Eur. J. med. Chem.-Chim. Ther., 1984, 19, 43). 

E-Caprolactam is an important starting material for the production of nylon-6. It is synthesized by the Beckmann rearrangement reaction of cyclohexanone oxime catalyzed by a solid acid catalyst. Many solid acid catalysts, such as mixed boron oxide [1-3], Si02-Al203 [4,5], metal phosphates [6-8] and moclified zeolites [3,9-12], are reported to catalyze the cycdohexanone oxime rearrangement. The acid function of the catalyst is essential to effect the rearrangement reaction. 

Poisoning experiments (at 573 K) in cyclohexanone oxime rearrangement over APTi-E-31 catalyst... 

Dehydroacetic acid, 652 reaction with, ammonia, 652 ethanolamine, 655 primary amines, 652 Dehydroacetic acid oxime, rearrangement of, in PPA,... 

Emser s mixed lactam process was understandably similar to that of Huels. The difference was that the steps of the process from oximation on oximation, rearrangement and initial purification, were done with a mixture of 6 and 12 carbon species. A mixture of cyclohexanone and CDON was fed to the oximation unit and allowed to remain mixed until caprolactam and lauryllactam were separated at the final step. This process had two main advantages the low melting, more-soluble C6 species acted as process solvents for the high melting, less-soluble C12 rings, and the output of two monomers provided economy of scale to a caprolactam plant of relatively low volume. This monomer process would be ideal for a producer of 6/12 copolymers. 

In this reaction, oximes rearrange to amides in the presence of protic or Lewis acids. Scheme 8.1 presents the mechanism for the Beckmann rearrangement of acyclic oxime 1 and cyclic oxime 2. The actual methods for the production of oximes are... 

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