Sulfonated enamines, hydrogenation

Alkyl sulfonyl chlorides, having an a-hydrogen atom, react with enamines derived from aldehydes and cyclic ketones in the presence of triethylamine to give cyclic sulfones. Thus the enamine (22) gave the four-membered cyclic aminosulfone (143) on reaction with methanesulfonyl chloride (95). 

The aromatic sulfonyl chlorides which have no a-hydrogen and thus cannot form sulfenes give acylic sulfones. Thus 1-piperidinopropene on reaction with benzene sulfonyl chloride (9J) gave 2-benzenesulfonyl-l-piperidinopropene (153). Similarly the enamine (28) reacts with p-toluene-sulfonyl chloride to give the 2-p-toluenesulfonylcyclohexanone (154) on hydrolysis (/OS). 

Methyl vinyl sulfone forms 1,2-cycloaddition adducts with aldehydic enamines, both with and without 3 hydrogens (37). Simple alkylation was reported to take place when phenyl vinyl sulfone was allowed to react with cyclohexanone enamines (58,60), but it has recently been shown that phenyl vinyl sulfone also forms cyclobutane adducts (60a). 

A benzazepine that includes the same (3-ketoamide array as piroxicam (Chapter 11) retains NSAID activity. Oxidation of benzothiapinone (5-1), obtainable by cycli-zation of 4-(4-chlorophenylthio)-butyric acid, with hydrogen peroxide gives the corresponding sulfone (5-2). This is then converted to its enamine (5-34) by reaction with pyrrolidine. Condensation of the intermediate with 3,4-dichorophenylisocyanate (5-4) leads to the amide (5-5). Hydrolysis with an aqueous acid cleaves the enamine function to give the keto-amide and thus enolicam (5-6) [6]. 

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