Alternative routes to the acylphloroglucinol rhodomyrtone

Abstract Two novel routes to the acylphloroglucinol rhodomyrtone ( 1 ) which has antibiotic properties are presented. In the first route an ortho -quinone methide, generated from dioxaborinine 23 , is reacted with syncarpic acid ( 10 ) leading to xanthenedione 25 . Cleavage of the methyl ether functions led to the known rhodomyrtone precursor 16 . In the second route the bis-ester derivative 28 of trihydroxybenzaldehyde 26 is condensed with syncarpic acid ( 10 ) to give tricyclic hemiacetal 29 . Acetalization and cuprate addition to the enone function led to bis-ester 32 which gave rhodomyrtone ( 1 ) by TiCl 4 -induced regioselective Fries rearrangement.