Alternative routes to the acylphloroglucinol rhodomyrtone

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 TiCl4-induced regioselective Fries rearrangement. (C) 2015 Elsevier Ltd. All rights reserved.