Synthesis of novel 4'-substituted 16-membered ring macrolide antibiotics derived from leucomycins

Synthesis and antibacterial activities of some novel 17, 18-unsaturated carbonyl compounds derivated from josamycin

Some novel josamycin derivatives bearing an arylalkyl-type side chain were designed and synthesized. By HWE or Wittig reaction, 16-aldehyde group of josamycin analogs were converted into unsaturated carbonyl compounds. They were evaluated for their in vitro antibacterial activities against a panel of respiratory pathogens. 8b and 8e exhibited comparable activities against a panel of respiratory pathogens, especially to resistant ones in the series of desmycarosyl josamycin analogs. Among of all the target molecules, 21 showed the best antibacterial activities.

Nitroso Diels-Alder (NDA) reaction as an efficient tool for the functionalization of diene-containing natural products

This review describes the use of nitroso Diels-Alder reactions for the functionalization of complex diene-containing natural products in order to generate libraries of compounds with potential biological activity. The application of this methodology to the structural modification of a series of natural products (thebaine, steroidal dienes, rapamycin, leucomycin, colchicine, isocolchicine and piperine) is discussed using relevant examples from the literature from 1973 onwards. The biological activity of the resulting compounds is also discussed. Additional comments are provided that evaluate the methodology as a useful tool in organic, bioorganic and medicinal chemistry.

Preparation and biological evaluation of novel leucomycin analogs derived from nitroso Diels-Alder reactions

A series of 10,13-disubstituted 16-membered macrolides was synthesized using nitroso Diels-Alder reactions of leucomycin A7. Despite the extensive constituent functionalities in leucomycin, the hetero cycloaddition reactions proceeded in a highly regio- and stereoselective fashion. Subsequent chemical modifications of the nitroso cycloadducts, including N-O bond reduction, were also conducted. Most leucomycin derivatives retained antibiotic profiles similar to leucomycin A7, and, in contrast to leucomycin itself, several exhibited moderate antiproliferative and cytotoxic activity.