D. A mixture of the cis-diester 3d (0.2 g, 0.65 mmol) with potassium permanganate (0.15 g, 0.98 mmol)
in acetonitrile (50 ml) was boiled for 12 h and was then kept at room temperature for 12 h. After the usual
treatment we isolated 0.11 g (55%) of a compound melting at 190-192°C and identical with the compound
obtained by method C.
E. A mixture of the cis-diester 3d (0.12 g, 0.39 mmol) with potassium permanganate (0.13 g,
0.78 mmol) in ethanol (50 ml) was boiled for 15 h and was then kept at room temperature for 48 h. We obtained
0.09 g (75%) of a compound melting at 190-192°C and identical with the compound obtained in experiments C
and D.
1-N-Methylamino-3-phenyl-3-propanone (5). A. To a solution of 4-phenyltetrahydropyridine 1a (1 g,
5.8 mmol) in aqueous acetonitrile (15 ml) over 15 min we added potassium permanganate (1.8 g, 11.6 mmol).
The mixture was stirred at 50-60°C for 8 h. The manganese dioxide was filtered off and washed with
acetonitrile (30 ml). The combined extracts were evaporated under vacuum, and the residue was separated by
chromatography. Yield 0.11 g (12%) of the secondary amine 5 in the form of a yellow oil (darkening with time);
H NMR spectrum, δ, ppm,
Rf 0.5 (acetone). 1
J (Hz): 2.15 (1H, br. s, NH); 2.20 (2H, t, J = 11.5, 2-H); 2.40 (3H,
s, Me); 3.83 (2H, t, J = 11.5, 1-H); 7.45-7.6 (3H, m, Ph); 7.79 (2H, d, J = 7.4, Ph). IR spectrum, , cm-1: 3450,
ν
3345 (NH), 2805 (NMe), 1678 (PhC=O). Mass spectrum, m/z (%):163 (3) [M+], 131 (8), 120 (30), 105 (100)
[PhCO]+·, 77 (83), 58 (45) [M–PhCO]+·, 44 (42) [CH2NHMe]+·, 43 (90). Found, %: N 8.37. C10H13NO.
Calculated, %: N 8.59.
B. The experiment was carried out similarly by heating at 50-60°C for 2 h and then holding the mixture
at room temperature for 24 h. Yield 0.18 g (20%) of the amine 5.
C. To a solution of the noncyclic amide 4a (0.78 g, 3.66 mmol) in ethanol (30 ml) we added manganese
dioxide (0.2 g, 5.5 mmol) and a 10% aqueous solution of sodium hydroxide (2 ml). The mixture was stirred at
room temperature for 8 h, the alcohol was distilled under vacuum, and the residue was extracted with
chloroform (3×20 ml). From the extract after removal of the solvent we isolated by chromatography 0.4 g
(60.6%) of an oily substance which was identical in its chromatographic mobility and spectral characteristics
with the secondary amine 5, obtained by the cascade oxidation of the tetrahydropyridine 1a by methods A
and B.
1-Benzyl-4-methyl-3,4-piperidinediol (1f). A solution of potassium permanganate (1 g, 6.4 mmol) and
magnesium sulfate (0.77 g, 6.4 mmol) in water (100 ml) was added to a solution of 1-benzyl-4-
methyltetrahydropyridine 1f (1.2 g, 6.4 mmol) in ethanol (40 ml) at such a rate that the temperature of the
mixture did not exceed 1°C. The mixture was stirred at this temperature for a further hour, and the manganese
dioxide was then separated and washed with ethanol (30 ml). The extracts were evaporated, and the residue was
extracted with hot chloroform (3×15 ml). The extract was purified on a column of silica gel, and 0.42 g (29%)
1
of the diol 6 was obtained in the form of a thick oil; Rf 0.8 (4:8:1 hexane–chloroform–ethanol). H NMR
spectrum, δ, ppm: 1.82-2.2 (2H, m, 5-H); 2.0 and 2.1 (1.5H each, both s, Me); 2.3-2.65 (4H, m, 2
- and 6-H);
2.73 (1H, m, 3-H); 2.8 and 3.9 (1H each, br. s, OH); 3.5 and 3.6 (1H each, both s, CH2Ar); 7.2-7.5 (5H, m, Ph).
Mass spectrum, m/z (%): 221 (10) [M+], 204 (5), 203 (4), 130 (7), 112 (4), 91 (100). IR spectrum: broad band
centered at 3330 cm-1. Found, %: C 70.8; H 8.89; N 6.57. C13H19NO2. Calculated, %: C 70.59; H 8.6; N 6.34.
1-Ethyl-4-methyl-3,4-piperidinediol-2-one (3e). An aqueous solution of potassium permanganate
(1.9 g, 12 mmol) was added to a solution of 4-methyl-1-ethyltetrahydropyridine 1e (1 g, 8 mmol) in acetone
(40 ml) over 20 min at 10°C. The mixture was stirred at room temperature for 30 min, and the manganese
dioxide was then separated and washed with acetone (40 ml). The filtrates were evaporated, and the residue was
extracted with chloroform (3×20 ml). From the extract after chromatographic separation 0.55 g (40%) of the
lactamdiol 3e was obtained in the form of a thick colorless oil. IR spectrum, , cm-1: 3350 (broad band);
ν
1640 (NC=O). Mass spectrum, m/z (%): 173 (42) [M]+; 156 (17) [M–OH]+·; 155 (15); 144 (35) [M–Et]+·;
126 (25) [M–Et–H2O]+·; 114 (25); 102 (30) [M–EtNCO]+·; 100 (58); 86 (100); 72 (58); 71 (55) [EtNCO]+·.
Found, %: C 55.12; H 9.03; N 7.81. C8H15NO3. Calculated, %: C 55.49; H 8.67; N 8.09.
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