Practical application of new catalytic methods: a concise synthesis of a potent PDE IV inhibitor

An efficient synthesis of a potent PDE IV inhibitor 1 is described. The synthesis is highlighted by two practical and efficient catalytic reactions: a highly selective catalytic palladium mediated carbonylation of the pyridine side chain and an efficient palladium-catalyzed Suzuki-Miyaura coupling of a chloropyridine-N-oxide.     

Strategic studies in the syntheses of novel 6,7-substituted quinolones and 7- or 6-substituted 1,6- and 1,7-naphthyridones

This paper describes the different strategies devised and applied to overcome the selectivity issues in the syntheses of 6,7-disubstituted-1H-quinolin-4-one, 7-substituted-1H-1,6-naphthyridin-4-one and 6-substituted-1H-1,7-naphthyridin-4-one derivatives. They allowed us to improve the overall yields and the scaling-up feasibility. Several examples illustrate these strategies with their advantages and drawbacks.     

Synthesis of naphthyridone derivatives containing 8-alkoxyimino-1,6-dizaspiro[3.4]octane scaffolds

The synthesis of naphthyridone derivatives containing 8-alkoxyimino-1,6-dizaspiro[3.4]octane scaffolds, the position isomers of the side chain at the C-7 position of Zabofloxacin, has been achieved in eight steps from tert-butyl 3-cyano-4-oxopyrrolidine-1-carboxylate. The possible reaction mechanisms were also proposed. The key spirocyclic carbamate esters, which could be prepared using a modified Hofmann rearrangement strategy, were condensed with naphthyridone nuclei, and the resulting condensates were easily cleaved by TMSI and subsequently cyclized in the presence of K₂CO₃. Moreover, additional N-methylation derivatives were also obtained using the synthetic sequence.