7-Substituted fused ring tetracycline

Patent 7-Substituted Fused Ring Tetracycline Compounds... 

Tetracyclines [tet ra SYE kleen] are a group of closely related compounds that, as the name implies, consist of 4 fused rings with a system of conjugated double bonds. Their small differences in clinical efficacy reflect a variation in their individual pharmacokinetics due to substitutions on these rings. 

Quinolone antibiotics such as ofloxacin 200 are totally different from P-lactams, tetracyclines and so on and work in a different way. They offer some hope that resistance may be slow to appear. They all contain the quinolone core a benzene ring fused to a y-pyridone. Most have various amine substituents and ofloxacin has a fluorine atom. Disconnection of the enamine reveals a benzene ring with a series of heteroatom substituents (N, N, O, F) and the one fluorine suggests that a series of nucleophilic substitutions might provide a synthesis. 

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