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Then, [Rh(CO)2Cl]2 (7 mg, 18 µmol) was added at rt, and the test-tube was sealed with a rubber
septum and heated to 35 °C in an oil bath. After 1 h, another portion of [Rh(CO)2Cl]2 (7 mg, 18
µmol) was added by briefly opening the reaction vessel, and heating was continued for 1 h.
During this time, the product of the reaction (177) partially percipitated from the solution as a
light orange solid. The precipitate was collected by filtering the reaction mixture through a small
pipette over a cotton plug. The filtrate was concentrated under vacuum and the crude residue was
purified by flash chromatography (hexanes-EtOAc, 9 : 1 to 0 : 1, v/v) to give 177 (60 mg, 58%
after combining with the portion obtained by filtration).
1 H NMR (300 MHz, CDCl3): δ 7.91-7.71 (bs, 1H), 7.55-7.39 (m, 5H), 6.33 (dd, J = 17.2, 10.7
Hz, 1H), 5.78 (q, J = 7.1 Hz, 1H), 5.62 (s, 1H), 5.47 (dd, J = 17.2, 1.3 Hz, 1H), 5.21 (dd, J =
10.7, 1.3 Hz, 1H), 4.41 (d, J = 14.5 Hz, 1H), 3.71 (d, J = 14.5 Hz, 1H), 1.75 (s, 3H), 1.60 (d, J =
7.1 Hz, 3H); 13 C NMR (75 MHz, CDCl3): δ 175.6, 171.6, 137.4, 135.5, 134.0, 130.4, 129.6,
128.5, 127.5, 124.6, 123.1, 118.0, 62.8, 43.7, 20.6, 13.3; IR (thin film): ν 2983, 2025, 1742, 1593
cm -1 ; MS m/z (%) 297 (7), 253 (67), 252 (80), 105 (100); EI-HRMS calcd for C18H19NO3 m/z
[M] + 297.1365; found 297.1372.
184: Synthesized according to the following scheme:
Cbz
O
N
OMe
Cbz
a N
OH
b
Cbz
111f 183 184
a) DIBALH (3 equiv.), CH 2Cl 2, -78 o C-rt; b) acryloyl chloride (1.2 equiv.), Et 3N (1.2 equiv.), CH 2Cl 2.
3-Ethylidene-6-hydroxymethyl-6-methyl-4-vinyl-3,6-dihydro-2H-pyridine-1-carboxylic acid
benzyl ester (183). A solution of 111f (50 mg, 0.15 mmol), in toluene (1 mL), was cooled to -50
226
O
N
O