Quinones. Part VIII. Dehydro-α- and -β-lapachone

Abstract

Dehydro-α- and -β-lapachone have been obtained from their leuco-diacetates by reaction with a Grignard reagent followed by oxidation of the resulting quinols with silver oxide and lead tetra-acetate, respectively. The dehydrolapachones were also derived from the corresponding α- and β-lapachones by dehydrogenation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Dehydro-α-lapachone is identical with “dehydrolapachone” in the literature. Dehydro-β-lapachone is very labile and prone to rearrange to the α-isomer which is the main product in both methods of preparation of the β-isomer.