Synthesis of 2-methoxystypandrone: comments on the structure of ventilaginone

Abstract
The structure of 2-methoxystypandrone a naphthoquinone isolated from Polygonum cuspidatum, Rhamnus fallax, and Ventilago calyculata is confirmed by synthesis as 6-acetyl-5-hydroxy-2-methoxy-7-methylnaphthalene-1,4-dione (1). The structure proposed for ventilaginone, an unusual naphthalene isolated from Ventilago maderaspatana, 8,9-dimethoxy-5-methylnaphtho [1,8-de]-1,3-dioxin-4-yl methyl ketone (17), is shown by synthesis to be erroneous. Alternative structures are considered.