Synthèse de l'évernine

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Abstract
Synthesis of EverninTwo syntheses of the depside evernin 6 are described. Condensation of methyl acetoacetate and methyl crotonate followed by aromatization and reduction with Raney‐Ni led to methyl orsellinate (3). The condensation of everninic acid (4), obtained by partial methylation of 3 and saponification of the methyl ester, with methyl 2, 4‐dihydroxy‐3, 6‐dimethylbenzoate (methyl β‐orcin carboxylate) (5) in presence of cyclohexylcarbodiimide gave evernin (6). In a second syntheis methyl dihydroorsellinate (1) was regiospecifically converted into its 4‐methyl enol ether and aromatized via the benzene selenenyl derivative to yield methyl evernate (7). Benzylation followed by saponification gave the free acid 8. Methyl β‐orcin carboxylate (5) was synthesized in an analogous way from methyl 3,6‐dimethyl‐2,4‐dioxocyclohexanecarboxylate. Condensation of 8 with the methyl ester 5 by treatment with trifluoroacetic anhydride in toluene yielded 9, which could be converted into evernin (6) by hydrogenolysis of the benzyl ether.