The Baeyer-Villiger reaction is an oxidative transformation of katones into esters by peracid,which is an important method for functional group transformation as well as for ring expansion in organic synthesis.Oxidation of cyclic ketones into lactones has been employed for heterocycles and functionalized carbon chains.The reaction is reliable for controlling the regioselectivity and stereochemistry of the products,it is widely used as a key ring expansion step for the synthesis of natural products,including antibiotics steroids and pheromones.Particularly many complex structure of oxyacids would be synthesized by lactones via hydrolysis.In this paper we reported that（+）-chrysanthenone（2）(\20D=+38.0) was obtained from crude（+）-verbenone without purification on the irradiation with ultraviolet light in Quartz flask.When（+）-chrysanthenone underwent Baeyer-Villiger oxidation by using oxidant H2O2and CH3COOH as the oxidant the lactone 2,8,8-trimethyl-6-oxo-7-oxabicyclo[3.2.1]oct-2-ene（3）(\20D=+65.0) was formed.Then compound 3 was hydrolysized to afford 2,2,4-trimethyl-5-hydroxycyclohexen-3-yl carboxylic acid（4）(\20D=+50.0).Compound 4 was oxidized by pyridinium chlorochromate to afford conjugated ketone acid 2,2,4-trimethy-3-oxocyclohexen-4-yl carboxylic acid 5.The structure of compounds 2,3,4,5 were identified by（）1H NMR,IR and chemical reaction.The mechanism of oxidation of lactone 3 in the Baeyer-Villiger reaction was discussed.In this reaction the migrating group is a secondary carbon group holding allyl function.
