Preparation of cyclic 2′,3′-carbamate derivatives of erythromycin macrolide antibiotics

Tricarbonylation of clarithromycin has been effected in a one-pot reaction with phosgene. The 11,12-diol moiety was closed into a cyclic carbonate, while the dimethylamino alcohol of the desosamine sugar was cyclised with loss of a methyl group to form a cyclic 2′,3′-carbamate. The 4″ hydroxyl group in clarithromycin was converted into a chloroformate group and subsequently to an allyl carbonate which on Pd-catalysis furnished a novel N-demethylclarithromycin 2′,3′-carbamate-11,12-carbonate. Hydrolytic removal of the cladinose sugar and a subsequent oxidation furnished the corresponding ketolide. The 11,12-cyclic carbonate moiety was cleaved by sodium azide to the 10,11-anhydro-9-ketone. 11-N-Arylated cyclic 11,12:2′,3′-dicarbamate derivatives were prepared in a copper(I) chloride aided reaction between aryl isocyanates and 10,11-anhydro 9-ketones. The products are novel N-arylated-N′-demethylated 11,12:2′,3′-dicarbamate ketolides derived from clarithromycin.