Oximes, rearrangement ketone

The oximes of ketones undergo the Beckmann rearrangement on treatment with phosphorus pentachloride (118). 

Beckmann Rearrangement results when oximes of ketones are treated with certain reagents such as phosphorus pentachloride. 

Oximes of ketones undergo rearrangement (the Beckmann rearrangement) to amides under the influence of a variety of acidic reagents (e.g. sulphuric acid, hydrogen fluoride, acetic anhydride, phosphorus pentachloride, thionyl chloride, etc.). The process is illustrated by the conversion of benzophenone oxime to benzanilide in the presence of phosphorus pentachloride. 

The procedure described is a one-step conversion of cycloheptanone into hexahydro-2(lH)-azocinone. The method is general and is characterized by good yields, mild conditions, and easy preparation of the product in pure form from readily available starting materials. Several methods are described in the patent literature for simultaneous oximation of ketones and rearrangement to the corresponding oxime, Including the use of hydroxylamine and sulfuric... 

Structures (316) with an oxetan ring, recently proposed250 for two iodo-compounds obtained during the hypoiodite reaction of cholesterol, have now been revised.251 Spectroscopic and X-ray data show the compounds to be iodo-acetals (317), converted by de-iodination and reaction with BF3-acetic anhydride into the dihydropyran (318). Photolysis of the oxime of a l,5-dien-3-one gave mainly rearranged ketonic products, isomers of type (319), which are also obtained by photo-rearrangement of the l,5-dien-3-one.252... 

In the Beckmann rearrangement (equation 6.108), oximes of ketones are converted to amides by acid catalysts. 

Usually, Beckmann rearrangement of oximes of ketones are converted into anilides by heating with acidic reagents like PCl, HCOOH, SOCI2 etc. However, solid-state Beckmann rearrangement has been reported. In this method oxime of a ketone is mixed with montmorillonite and irradiated for 7 min in a microwave oven to give corresponding anilide in 91% yield (Scheme 24). 

Oximoxytris(dimethylamino)phosphonium salts, derived from oximes of ketones, undergo the Beckmann rearrangement. ... 

A special experiment shows [343] that N-benzylbenzamide is not a product of oxime rearrangement (upon heating oxime under the same conditions without acetylene, it is nearly completely recovered). Obviously, the key role in the formation of amide from benzyl phenyl ketone belongs to acetylene. 

The PdCli-catalyzed instantaneous rearrangement of A -carbethoxy-S-azabi-cyclo[5.1.0]oct-3-ene (60) takes place at room temperature to give A -car-bethoxy-8-azabicyclo[3.2.1]oct-2-ene (61)[50], The azepine 62 undergoes a smooth skeletal rearrangement to give 63, and the diazepine 64 is converted into the open-chain product[51]. Beckmann fission of the oxime 65 of ketones and aldehydes to give the nitrile 66 is induced by a Pd(0) complex and oxygen [52,53]. 

One of the more important approaches to 1-azirines involves a similar base-induced cycloelimination reaction of a suitably functionalized ketone derivative (route c. Scheme 1). This reaction is analogous to route (b) (Scheme 1) used for the synthesis of aziridines wherein displacement of the leaving group at nitrogen is initiated by a -carbanionic center. An example of this cycloelimination involves the Neber rearrangement of oxime tosylate esters (357 X = OTs) to 1-azirines and subsequently to a-aminoketones (358) (71AHC-(13)45). The reaction has been demonstrated to be configurationally indiscriminate both syn and anti ketoxime tosylate esters afforded the same product mixture of a-aminoketones... 

Rearrangement of N.N-dimethyttiydrazone or tosylate derivatives of oxime to azirines and from there to a-amino ketones. 

Schopf has also obtained direct evidence for the location of th carbon end of the ethanamine chain by submitting dihydrocodeinoneoximr to a Beckmann rearrangement. This process, the steps in which an illustrated by partial formal for ring III, should provide an aldehydt (XLVc) if the oxime is correctly represented by the Gulland and Robinsoi formula (XLVb) and a ketone (XLVIc) if it has the structure (XLVIb required by the Wieland and Kotake formula. 

Substituents R, R at the starting oxime 1 can be H, alkyl, or aryl. The reaction conditions for the Beckmann rearrangement often are quite drastic (e.g. concentrated sulfuric acid at 120 °C), which generally limits the scope to less sensitive substrates. The required oxime can be easily prepared from the respective aldehyde or ketone and hydroxylamine. 

An a-amino ketone, obtained by the Neber rearrangement, can be further converted into an oxime tosylate, and then subjected to the Neber conditions a ,a -diamino ketones can be prepared by this route. 

The monomer (laurolactam) could he produced from 1,5,9-cyclododeca-triene, a trimer of hutadiene (Chapter 9). The trimer is epoxidized with peracetic acid or acetaldehyde peracetate and then hydrogenated. The saturated epoxide is rearranged to the ketone with Mgl2 at 100°C. is then changed to the oxime and rearranged to laurolactam. 

Neber oxime tosylate-amino ketone rearrangement... 

Not only do oximes undergo the Beckmann rearrangement, but so also do esters of oximes with many acids, organic and inorganic. A side reaction with many substrates is the formation of nitriles (the abnormal Beckmann rearrangement, 17-31). Cyclic ketones can be converted directly to lactams in one laboratory step by... 

---