Dipentene allylic oxidation

Examples of the use of chromium(VI) reagents to effect the allylic oxidation of alkenes to give a,3-unsaturated carbonyl compounds are very common in the literature. The reaction was first reported by Treibs and Schmidt for the allylic oxidations of a-pinene to verbenone and verbenol, of dipentene to carvone and caiveol, and of cyclohexene to cyclohexenol and cyclohexenone, using a solution of chromium trioxide in a mixture of acetic anhydride and carbon tetrachloride. However, yields were low and no synthetic use of this observation was made. 

Using the most active catalyst (CoNaY) we have studied the oxidation of olefins of different structure and size of molecules, including a number of natural terpenes, namely, (+)-a-pinene (1), (+)-3-carene (2), (-)-caryophyllene (3) and dipentene (4). We have found that even acid-sensitive epoxides that are known to be prone to ring cleavage (caryophyllene epoxide, for example) can be obtained with high-to-exceUent selectivity (Table 2). It is noteworthy that neither allylic oxidation nor overoxidation occurs in the systems studied. Diolefins give mono-... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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