A series of novel 7-piperazinyl-1-substituted-6-fluoroquinolones and naphthyridines have been prepared and their antibacterial activities evaluated. These derivatives are characterized by having alkyl, alkenyl, arylalkyl, cycloalkyl, and cycloalkenyl groups at the 1-position. As a result of this study, derivatives 7 and 26, which are substituted with tert-butyl groups at N-1, were found to possess excellent in vitro and in vivo potency, particularly against Staphylococcus aureus, comparable to that of norfloxacin or ciprofloxacin. Structure-activity relationships of N-1 substituted alkyls and cycloalkyls are also discussed.

A number of 7-substituted-1-tert-butyl-6-fluoroquinolone-3-carboxylic acids and 7-substituted-1-tert-butyl-6-fluoro-1,8-naphthyridine-3-carboxylic acids have been prepared and tested for antibacterial activities. Among those the 7-aminopyrrolidinyl 20b and the 7-diazabicyclo naphthyridine 18b are the most potent compounds in vitro and in vivo. Physicochemical data and acute toxicity are also discussed. Compound 18b, BMY 40062, exhibits the most favorable overall properties, considering in vitro and in vivo microbiological activity, its low toxicity, and pharmacokinetic profile, and was selected for clinical evaluation.

An anthracene–acetylene cyclic dimer with an intra-annular ethyl group was synthesized as a sterically congested π-conjugated compound by cyclization with Sonogashira coupling. The ethyl group was conformationally cramped by the rigid macrocyclic framework because of the severe steric interactions, as revealed by 1H NMR spectroscopy and DFT calculation.

The iodocyclization of γ,δ-unsaturated alcohols in the presence of a silyl enol ether produced cis-2,5-disubstituted tetrahydrofurans in one pot via siloxy intermediates. N-Iodosuccinimide (NIS) effectively worked as an activator of the double bonds in the substrates and the silyl enol ether. Application to an expedient synthesis of the adjacent bis-tetrahydrofuran core of Annonaceous acetogenins with a cis/threo/cis relative stereochemistry is also described.

A novel and rapid approach to chiral mono- or di-substituted spiroketals based on remote asymmetric induction by intramolecular iodoetherification of ene or diene ketals has been developed. This strategy concisely offers 5,5- and 5,6-spiroketals including the natural insect pheromone of the wasp.