Khellin oxidation

The oxidation of the cyclic enol ether 93 in MeOH affords the methyl ester 95 by hydrolysis of the ketene acetal 94 formed initially by regioselective attack of the methoxy group at the anomeric carbon, rather than the a-alkoxy ketone[35]. Similarly, the double bond of the furan part in khellin (96) is converted ino the ester 98 via the ketene acetal 97[l23],... 

The fiiran ring in khellin and cyclic ethers in sugars were oxidized to esters in methanol (Scheme 25),3s,i23 xricyclo [4.2.2.0 ]deca-3,7-diene-9,10-dicarboxylate (84) was oxidized to the monoketone in 7 h as a primary product, which was further oxidized to the diketone in 10 h in high yield with a stoichiometric amount of Pd(N03)2 in refluxing methanol (equation 14), ... 

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