Scalable Synthesis of Mycocyclosin.

We report herein the scalable total synthesis of the secondary metabolite, mycocyclosin, initially isolated from Mycobacterium tuberculosis. Mycocylosin bears a highly strained 3,3'-dityrosine biaryl system which arises biosynthetically from an intramolecular oxidative dehydrogenative cross-coupling of cyclo(l-Tyr-l-Tyr) (cYY) catalyzed by the P450 enzyme CYP121. CYP121 is found exclusively in M. tuberculosis. Scalable access to mycocyclosin and related derivatives via a Pd(II)-catalyzed macrocyclization is anticipated to facilitate the biological evaluation of these compounds as novel tuberculosis antimicrobials.