Methyl N-(4-methylpyridin-3-yl)carbamate → methyl N-[(3S,4S)-4-methylpiperidin-3-yl]carbamate

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Reaktionsschritte

The hydrogenation was carried out by charging 5 grams (1 equiv., 30.1 mmol) (4-methyl-pyridin-3-yl)-carbamic acid methyl ester, 50 ml ethanol (10 volumes), and 2.5 grams rhodium on alumina (0.5 wt. equivs.) to a bomb hydrogenator. The hydrogenation was performed under 100 psi hydrogen at 100° C. for 24 hours to give only cis-(4-methyl-piperidin-3-yl)-carbamic acid methyl ester and its trans isomer (5:1 ratio) in quantitative yield. 1 H NMR: δ5.6 (1 H, d, J=8.4 Hz), 3.66 (1 H, d, J=3.6 Hz), 3.65-3.57 (3 H, brs), 3.1 (2 H, d, J=9.6, minor isomer), 2.91-2.86 (2 H, m), 2.67-2.64 (1 H, m), 2.54-2.43 (1 H, m), 2.2-1.9 (1 H, m, minor isomer), 1.78-1.65 (5 H, brs, minor isomer), 1.65-1.59 (4 H, m, minor isomer), 1.36-1.25 (2 H, m), 1.24-1.13 (2 H, m), 0.92 (3 H, d, J=6.8 Hz, minor isomer), 0.83 (3 H, d, J=7.2).

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