ABSTRACT
Unprecedented tandem allylic alkylation/intermolecular Michael addition was used in the preparation of novel bicyclic azalides. NMR spectroscopy was used not only to unambiguously determine and characterize the structures of these unexpected products of chemical reaction but also to investigate the effect the rigid bicyclic modification has on the conformation of the whole molecule. Thus, some of the macrolides prepared showed antibacterial activity in the range of well-known antibiotic drug azithromycin.
Subject(s)
Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Macrolides/chemistry , Alkylation , Catalysis , Gram-Negative Bacteria/drug effects , Gram-Negative Bacteria/isolation & purification , Gram-Positive Bacteria/drug effects , Gram-Positive Bacteria/isolation & purification , Humans , Macrolides/chemical synthesis , Macrolides/pharmacology , Magnetic Resonance Spectroscopy , Microbial Sensitivity Tests , Molecular Structure , Palladium/chemistry , StereoisomerismABSTRACT
The stability in aqueous solution of five classes of coumarin dimers (I-V, compounds 1-29) was studied by HPLC-MS/MS at various pH values. The relationship between chemical structure and stability is discussed. It was found that dimeric compounds with strong electron withdrawing groups (EWGs) on the α-carbon to the bridging C-atom are stable at all pH values, whereas other derivatives undergo retro-Michael addition at rates which are also affected by the substituents on the aromatic rings. In some cases formation of stable isomers or oxidation products was observed. In order to evaluate their developability and potential for progression to in vivo studies, representative compounds were tested in an in vitro microsomal stability assay.
