Solutions For An Introduction to Medicinal Chemistry Chapter 19 Problem 11Q

These are basically used to cure urinary tract infections. The ciprofloxacin consist of cyclopropane attached to first nitrogen. It gives broad spectrum properties to the ciprofloxacin. The nitrogen is replaced by carbon and decreases its adverse action. These properties differentiate ciprofloxacin from other analogues. The mechanism of synthesis of ciprofloxacin is as follows:

Figure: The mechanism of synthesis of ciprofloxacin.

2, 4-dichloro-5-fluro-benzoyl chloride and diethyl malonate reacts in presence of magnesium ethoxide and produces diethyl (2,4-dichloro-5-fluro-benzoyl) malonate. It then presence of 4-toluenesulphonic acid produces ethyl 2, 4-dichloro-5-fluro-benzoylacetate.

Ethyl 2, 4-dichloro-5-fluro-benzoylacetate produces ethyl 2-(2,4-dichloro-5-flurobenzoyl)-3-ethoxyacrylate in presence of triethyl orthoformate. Ethyl 2-(2, 4-dichloro-5-flurobenzoyl)-3-ethoxyacrylate reacts with cyclopropyl-amine and produces ethyl-3-cyclopropylamino-2-(2, 4-dichloro-5-fluro-benzoyl) acrylate.

In presence of sodium hydride it gives rise to 7-chloro-1-cyclopropyl-6-fluro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid. It further reacts with piperazine in presence of dimethyl sulfoxide and produces ciprofloxacin.