合成路线1

The reaction of 4-benzoyloxycyclohexanone (I) with pyrrolidine (II) by means of p-toluenesulfonic acid in refluxing benzene gives the corresponding enamine (III), which is cyclized with acrylamide (IV) in refluxing dioxane yielding the mixture of hexahydroquinolones (V) and (VI). Benzylation of this mixture with benzylbromide (A) and NaH in THF affords the mixture of N-benzylquinolones (VII) and (VIII), which is reduced with LiAlH4 to the mixture of N-benzylhexahydroquinolines (IX) and (X). The reduction of this mixture with sodium cyanoborohydride in THF affords trans-1-benzyl-6-hydroxydecahydro quinoline (XI), which by reaction with BN in CH2Cl2 is converted to trans-1-cyano-6-hydroxydecahydro quinoline (XII). Oxidation of (XII) with CrO3/pyridine in CH2Cl2 gives the corresponding quinolone (XIII), which by reaction with dimethylformamide dimethyl acetal (XIV) in refluxing benzene is converted to 1-cyano-6-oxo-7-(dimethylaminomethylene)decahydroquinoline (XV). The cyclization of (XV) with hydrazine in refluxing methanol affords 5-cyano-4,4a,5,6,7,8,8a,9-octahydro-1H-pyrazolo[3,4-g]quinoline (XVI), which by a reductive cleavage with Zn and acetic acid gives 4,4a,5,6,7,8,8a,9-octahydro-1H-pyrazolo[3,4-g]quinoline (XVII). Finally, this compound is alkylated with propionaldehyde (B) and sodium cyanoborohydride in methanol.