The second way of synthesizing baclofen is started from ethyl ester of 4-chlorocinnamic acid. Adding nitromethane to this in the presence of base gives ethyl ester of /¡-(4-chlorophenyl)-}-nitrobutyric acid (15.3.6), the nitro group of which is reduced by hydrogen over Raney nickel to the ethyl ester of /¡-(4-chlorophenyl)-y-aminobutyric acid (15.3.7), which is further hydrolyzed into the desired baclofen (15.3.5) .
/=\ CH3NO2 /==\ CH2-N02 [H] /=> ch^nh2 Na0H CI—h— CH=CH-C00C2H5 -»- CI—^ h—cCH -»- CI—6 V-CH -»- 15.3.5
Baclofen is a substituted analog of GABA. It is presumed that its action consists of a reaction with GABA receptors, which leads to an inhibition of stimulatory neurotransmitter release.
Signs of muscle spasticity have been shown in disseminated sclerosis and other spinal disorders. It may be useful to patients with muscle spasms resulting from spinal cord injuries. A synonym of this drug is lioresal.
Cyclobenzaprine: Cyclobenzaprine, N,N-dimethyl-3-(dibenzo[a,d]cyclohepten-5-ylidene) propylamine (15.3.9), is synthesized by reacting 5H-dibenzo[a,d]cyclohepten-5-one with 3-dimethylaminopropylmagnesium chloride and subsequent dehydration of the resulting carbinol (15.3.8) in acidic conditions into cyclobenzaprine (15.3.9) [30-32].
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