A route to 1,4-disubstituted aromatics and its application to the synthesis of the antibiotic culpin

A method is described for converting tert-butyl benzoates or tert-butyl 1-naphthoates into derivatives having an alkyl or substituted alkyl group in a 1,4-relationship to an alkyl, aryl, alkenyl, or alkynyl group. Key steps in the sequence are (i) addition of an organometallic species to a cross-conjugated cyclohexadienone obtained by Birch alkylation of a tert-butyl benzoate or a tert-butyl 1-naphthoate, followed by allylic oxidation, and (ii) treatment with BiCl3 center dot H2O, which results in removal of the tertbutyl group and spontaneous decarboxylative aromatization. The method was applied to the synthesis of the antimicrobial fungal metabolite culpin.