Extender Groups other than Malonate

The use of propionate as a starter group as in the formation of the anthracyclines is perhaps 

I (i) glycosylation of 7-hydroxyl (ii) hydrolysis of ester (Hi) decarboxylation of 10-acid (iv) oxidation to 13-ketone T (v) methylation of 4-hydroxyl 

Bacterial resistance to erythromycin has become significant and has limited its therapeutic use against many strains of Staphylococcus. Several mechanisms of resistance have been 

Both malonyl-CoA and methylmalonyl-CoA are then utilized as extender units. The heterocyclic rings are easily accounted for the spiro system is merely a ketal, though the tetrahydrofu-ran ring requires further hydroxylations of the basic skeleton for its construction. Avermectins are usually isolated as a mixture in which the main a component has a 2-methylpropyl group 

Even larger macrolides are encountered in the polyene macrolides, most of which have antifungal properties, but not antibacterial activity. The macrolide ring size ranges from 26 to 38 atoms, and this also accommodates a conjugated polyene of up to seven E double bonds. Relatively 

---