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87%). The diastereomeric ratio (288c : 287c = 2.1 : 1) was determined by integration of the two
olefinic resonances in the 1 H NMR spectrum.
287c has been characterized previously from the Mo-mediated cyclocarbonylation reaction of
74c. Separation of 288c from 287c was achieved by HPLC (35 % EtOAc/hexanes, flow rate 3
mL/min, UV detection at 254 nm) with the following retention times: 288c (15.15 min); 287c
(15.62 min).
288c: 1 H NMR (300 MHz, CDCl3): δ 7.61-7.59 (m, 2H), 7.54-7.44 (m, 3H), 6.17 (d, J = 1.9 Hz,
1H), 5.54 (s, 1H), 4.58 (d, J = 14.9 Hz, 1H), 4.30 (d, J = 14.9 Hz, 1H), 3.76 (s, 1H), 3.55 (s, 3H),
2.04 (s, 3H), 1.77 (s, 3H); 13 C NMR (75 MHz, CDCl3): δ 195.4, 171.2, 170.5, 162.7, 140.2,
135.9, 135.1, 131.0, 128.6, 127.5, 118.0, 68.3, 55.0, 52.1, 50.3, 23.6, 9.1; IR (thin film): ν 2950,
1734, 1707, 1689, 1643, 1378 cm -1 ; MS m/z (%) 325 (10), 266 (18), 105 (100); EI-HRMS calcd
for C19H19N1O4 m/z [M] + 325.1314; found 325.1308.
Bz
N
MeO MeO2C 2C
2-Benzoyl-3,4,7-trimethyl-6-oxo-2,3,5,6-tetrahydro-1H-[2]pyrindine-3-carboxylic acid
methyl ester (329). To a solution of allenyne 328 (31 mg, 0.10 mmol) in DCE/toluene (3 mL, 9 :
1) in a 15 mL test tube was added [Rh(CO)2(dppb)]BF4 (3 mg, 5 µmol) under Ar atmosphere.
The test tube was sealed with a rubber septum and CO (3 mL) was injected via syringe. The
reaction vessel was heated to 80 °C for 6 h, and then cooled to rt. Purification by flash
chromatography (hexanes-EtOAc, v/v) afforded 329 (16.5 mg, 48%).
1 H NMR (300 MHz, CDCl3): δ 7.50-7.40 (m, 5H), 4.84 (d, J = 17.6 Hz, 1H), 4.01 (d, J = 17.7
Hz, 1H), 3.73 (s, 3H), 3.01 (d, J = 20.1 Hz, 1H), 2.94 (d, J = 20.1 Hz, 1H), 1.79 (s, 3H), 1.76 (s,
329
279
O