Rosaramicin aglycone

Total syntheses of the following antibiotics and/or their aglycones are dealt with methymycin, erythromycin, pikromycin, oleandomycin, ingramycin (albo-cycline), carbomycin B, leucomycin A3 (josamycin), tylosin, mycinamicins, rosaramicin, A26771B and elaiophylin (azalomycin B). Since the total synthesis of the macrolide-like immunosuppressant FK-506 has been recently reported, it is also reviewed here. Today, erythromycin A, oleandomycin, leucomycin A3 (josamycin), tylosin and mycinamicin II are clinically important antibiotics. 

Biosynthetically blocked mutants have also been obtained with the structurally-related macrolides rosaramicin and mycinamicin (see Fig. 6) [79, 80]. The biosynthetic precursor aglycones, 20-deoxo-rosaranolide and its des-epoxy analog, were isolated from an antibiotic-negative mutant strain and shown to be bioconverted to rosaramicin by an appropriate mutant of Micromonospora rosaria [79]. Proposed acyclic intermediates in the biosynthesis of mycinamicin have also been recently reported [81]. 

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