Ketones or ketals were readily converted into the corresponding gem-dihydroperoxides in high yields by treatment with ethereal H(2)O(2) at ambient temperature in the presence of 2-5 mol % of phosphomolybdic acid.

Attachment of H(2)O(2) onto the highly hindered quaternary C-12a in an advanced qinghaosu (artemisinin) precursor has been achieved through a facile perhydrolysis of a spiro epoxy ring with the aid of a previously unknown molybdenum species without involving any special equipment or complicated operations. The resultant β-hydroxyhydroperoxide can be further elaborated into qinghaosu, illustrating an entry fundamentally different from the existing ones to this outstanding natural product of great importance in malaria chemotherapy.

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