Chemical modification of spiramycins. II. Synthesis and antimicrobial activity of 4'-deoxy derivatives of neospiramycin I and their 12-(Z)-isomers

4'-Deoxy derivatives of neospiramycin I and their 12-(Z)-isomers were synthesized by reductive dechlorination via 4'-epi-chloro derivatives. The 12-(Z)-derivatives were more active against bacteria in vitro than the corresponding 12-(E)-derivatives in spite of their low affinities to ribosomes.