Aliphatic V-Substituted Imines

2 g Pt oxide prereduced in 50 ml EtOH 50 ml absolute EtOH/3 ml PrNH2 

Archer et al. obtained 3a-A-(2-diethylaminoethyl)aminotropane (4) in 85% yield by hydrogenation of the imine 3, prepared from the reaction of tropinone (1) with 2-diethylaminoethylamine (2), over platinum oxide in ethanol at room temperature (eq. 8.3).4 The same hydrogenation was also carried out over Raney Ni at 60°C and 6.9 MPa H2. The product was converted directly to the phenyl thioureide without isolating the amine. Compound 4 was also obtained in a 66% yield by hydrogenating the imine 3, which had been prepared in situ in ethanol by allowing a mixture of 1 and 2 to stand for 2 h, over prereduced platinum oxide mostly at room temperature and finally at 50°C to finish the reaction. In a large-scale run in methanol, a 77.8% yield of 4 was obtained (eq. 8.3). It was noticed that it was not necessary to prereduce Adams platinum oxide when the ketone and the amine were premixed, since the induction period could be eliminated by this procedure. 

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