Benzazepine Preparations of Potential Use in Rhoeadine Synthesis

The isomeric cis and trans benzazepinols 21 and 22 have been synthesized in good yields from the known keto ester 20  

Reduction with zinc in propionic acid of the ketoimmonium or the keto-ammonium salts 23 and 24 lead to benzazepine 25.  

A substituted benzazepine was formed by Friedel-Crafts cyclization of the toluenesulfonamide 27. The resulting ketone was reduced to the alcohol, and detosylation was achieved using sodium in liquid ammonia. The amino ketone 29 was also obtained by oxidation of 28 after protection of the amino function.  

Finally, diketospirobenzylisoquinolines can be rearranged in one step to dibenzocyclopentazepines by means of zinc in hot acetic acid. (See Sec. 25.3.) 

Hofmann degradation of rhoeagenine methiodide yields a complex mixture from which compounds 31-34 have been isolated and characterized.  

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