Oxidation of -camphor

The following oxidation of camphor to camphor-quinone illustrates the oxidising action of selenium dioxide, and readily gives a crystalline product. 

The cyclized analog of meralluride is prepared by a similar synthesis. Thus, condensation of camphoric acid (42) (obtained by oxidation of camphor) with ammonia gives the bicyclic succinimide (44). Reaction with allyl isocyanate followed by ring opening and then reaction with mercuric acetate affords the mercury derivative (45) as the acetate rather than the hydroxide as above. Reaction with sodium chloride converts that acetate to the halide (46). Displacement on mercury with the disodium salt of thioglycollic acid affords the diuretic mercaptomerine (47). ... 

An oxazoline AT-oxide is a versatile dipole and can react with a variety of dipolarophiles (Scheme 8.134). Langlois group has been very active in this area and has made extensive use of the Ai-oxides of camphor-derived oxazolines for these reactions. The initial adduct can be converted to the anti aldol product after hydrolysis and hydrogenolysis. This subject has been thoroughly reviewed by Langlois, " most recently in 2000. " ... 

Haller, 1896 started with camphoric acid prepared by the oxidation of camphor as illustrated in Scheme II. 

Some powerful oxidizing agents are able to cleave C-C bonds, as you will see in Chapter 35. Oxidation of camphor in this way produces a diacid known as camphoric acid. The usual reagent is nitric acid (HN03) and oxidation goes via camphor s enol. 

Constitution of Camphor.—The constitution of camphor and of Bomeol has been established by Kompa s synthesis of camphoric acid which is obtained by the oxidation of camphor. 

In the laboratory of T.-J. Lu, a highly stereoselective method for the asymmetric synthesis of a-amino acids was developed by the alkylation of a chiral tricyclic iminolactone derived from (+)-camphor. The iminolactone can be considered a glycine equivalent. The synthesis commenced with the Riley oxidation of (+)-camphor to obtain the corresponding (+)-camphorquinone. Amino acids are obtained by first alkylating the a-position of the lactone with various alkyl halides and then hydrolyzing the monosubstituted products. The advantage of this technique was that the chiral auxiliary could be fully recovered without the loss of any optical activity. 

Chiral N-sulfonyloxaziridines are useful reagents for the asymmetric synthesis of sulfoxides, selenoxides, and other substrates. Davis and co-workers <97JOC3625> have reported the first example of an e.vtt-camphorylsulfonyloxaziridine 175. prepared by the MCPBA oxidation of camphor inline 174 in the presence of potassium hexamethyldisilazide. This compound was then studied in various asymmetric oxidation applications. 

Oxidation of camphor with nitric acid opens the six-membered ring, affording cis-and irarw-camphoric acid. Sulfonation of camphor with concentrated sulfuric acid and acetic anhydride selectively yields 10-camphorsulfonic acid. 

Tricyclanes and Quadricyclanes.—Oxidation of camphor hydrazone with silver carbonate on celite gave the tricyclane (565) and a trace of bomylene, whereas other hydrazones are found to rearrange to azines. Diazocamphor (566) in THF is decomposed by catalytic silver perfluorobutyrate and affords the tricyclanone (567) in nearly quantitative yield the a-ketocarbene is the presumed intermediate. The carbomethoxylation of a-bonded organomercurials in the presence of stoicheio-metric amounts of lithium tetrachloropalladate and CO occurs with predominant retention of configuration at carbon. Thus (568) gave (569 38 %) and various minor components. 

The radical mechanism is further supported by several other results in which stereochemical scrambling and isotope scrambling are observed in the sMMO-catalyzed hydroxylation of hydrocarbons. Retention of stereochemistry is a valid measure of the concertedness of a reaction only if it can be assumed that the retention is not due to constrains imposed by the active site geometry of the enzyme. Loss of stereochemistry is absolutely indicative of a reaction requiring an intermediate and thus implies a nonconcerted reaction [2]. Scrambling of stereochemistry was observed with hydroxylation of c/5-l,4-dimethylcyclohexane and c/ -l,3-dimethylcyclohexane with sMMO system from Af. capsulatus (Bath) as shown in eqs. (7) and (8) [75]. This type of stereochemical scrambling was also observed in the hydroxylation of norbornane by rabbit liver microsomes and in the oxidation of camphor by cytochrome P-450 [2]. 

Reissell et al. (2001) measured a first generation yield of 29 4% of acetone in the OH-initiated oxidation of camphor in the presence of NO and air. They ascribed its formation to a mechanism involving abstraction at the tertiary bridgehead carbon, followed by ring-opening of the resulting oxy radical ... 

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