An integrated approach to the synthesis of continguously substituted xanthopurpurins, pachybasins and purpurins

Article abstract of DOI:10.1016/S0040-4020(01)80322-7

Alkylation, hydroxyalkylation and acylation of 3-methyl-, 3-methoxy- and 3,4-dimethoxycrotonates can be induced to occur exclusively in the α-position. Conversion of the products to dienes then provides, through cycloaddition, a wide variety of substitution patterns. This approach is illustrated by simplified syntheses of a number of naturally occurring quinones and confirms the structures proposed for vismiaquinone C, 7-geranylemodin, cinnalutein, 4,5-dihydroxydigitolutein, 2-hydroxyislandicin 1-methyl ether and calyculatone 1-methyl ether.