CpMoCo2(CO)8CCO+: Synthesis and characterization of a mixed metal acylium cation

Chlorine-35 and proton NMR study of anion binding to reduced bovine copper-zinc superoxide dismutase

“…This protein is an extremely efficient catalyst of superoxide dismutation (202" + 2H+ -* 02 + H202), and it has been proposed that this activity is its primary physiological function in vivo. 2 The reactive site is the Cu ion, which undergoes alternate reduction and oxidation during the catalytic cycle. A great deal of structural information is available for this protein in that both its amino acid sequence3 and X-ray crystal structure (oxidized form only) at 2-Á resolution4 are known.…”

Synthesis and asymmetric reactivity of enantiomerically pure cyclopentadienylmetal complexes derived from the chiral pool

“…Synthesis of 4. Because the structure of the camphor-derived diene 4 incorporates a rigid chiral auxiliary fused to the cyclopentadienyl moiety, it was of particular interest to examine this ligand in potentially enantioselective CpM-mediated transformations. A synthesis of 4 had been reported previously,13 but attempts to repeat the published preparation on a scale larger than described failed.…”

“…The product was purified by chromatography on activity 3 alumina under nitrogen with degassed solvents (pentane). A single red fraction was collected which afforded 23 as a red oil (1.255 g, 65.0%): IR (thin film) 2958,2903,2003,1944,1596,1491,1434,1361,1037,796,693 cm"1; MS, m/z (relative intensity) 394 (M+, 0.1), 366 (1), 338 (18), 119 (100), 105 (6), 95 (8), 91 (27), 84 (10), 81 (11); HRMS caled for C^H^CoO;,, 394.1343, found, 394.1331; NMR (300 MHz, C6D6) 7.16 (m, 2 ), 7.03 (m, 3 H), 4.28 (br s, 3 ), 4.11 (br s, 1 ), 2.15 (br d, J = 10.5 Hz, 1 H), 1.85 (br dd, J = 11, 10.5 Hz, 1 ), 1.60 (m, 3 ), 1.28 (m, 2 ), 1.10 (s, 3 ), 1.05 (s, 3 ), 0.97 (d, J = 6.4 Hz, 3 H), 0.75-1.00 (m, 2 H); 13C NMR (75.5 MHz, C6D6, DEPT) 151.8 (quat), 128.1 (CH), 126.0 (CH), 125.0 (CH), 118.9 (quat), 85.5 (CH), 83.3 (CH), 83.0 (CH), 80.6 (CH), 53.2 (CH), 51.6 (CH2), 41.0 (quat), 38.8 (CH), 35.6 (CH2),33.6 (CH), 29.2 (CH2), 28.1 (CH3), 25.9 (CH3), 22.3 (CH3).…”

“…A solution of 4 (0.261 g, 1.50 mmol) in a mixture of 1,2-dichloroethane and 1-pentene (15 mL, 2:1) was degassed by three freeze-pump-thaw cycles and then added to Co2(CO)8 (0.283 g, 0.82 mmol). After the mixture had been heated at reflux under nitrogen for 40 h, a thick oil was obtained and purified by chromatography on activity 3 alumina (hexanes) under nitrogen to give 25 (3:1 mixture of diastereomers) as a red oil (0.240 g, 55.5%): IR (thin film) 2962,2011,1955,1619,1453 cm"1; MS, m/z (relative intensity) 288 (M+, 12), 260 (22), 232 (32), 188 (35), 159 (13), 131 (26), 129 (24), 115 (21); HRMS caled for C16H17Co02, 288.0560, found, 288.0551; NMR ( 200MHz, C6D6) for major isomer, 4.55 (br d, J = 2.1 Hz, 1 ), 4.50 (br d, J = 2.2 Hz, 1 H), 3.98 (dd, J = 2.2, 2.1 Hz, 1 ), 1.40-2.10 (m, 5 ), 0.86 (s, 3 ), 0.67 (s, 3 ), 0.42 (s, 3 H), for minor isomer, 4.54 (m, 1 ), 4.10 (m, 2 ), 1.40-2.25 (m, 5 ), 1.02 (s, 3 H), 0.65 (s, 3 ), 0.33 (s, 3 H). Alternatively, 4 (0.523 g, 3.00 mmol) was deprotonated with butyllithium (1.94 mL, 1.55 , 3.00 mmol) at 0 °C and then exposed to ICo(CO)4 [generated by combining Co2(CO)8 (0.513 g, 1.50 mmol) and I2 (0.380 g, 1.50 mmol) in hexane (0 °C, 1 h)].…”

“…A solution of 23 (0.065 g, 0.17 mmol) and 32 [R1 = Si(CH3)3, R2 = CH3] (0.047 g, 0.22 mmol) in THF (50 mL) was treated as described above to give a diastereomeric mixture of products as a red oil (0.060 g, 63.8%, ratio 67:33). Separation by flash chromatography (5% methanol in ether) produced a minor isomer first (0.018 g) as a red oil: IR (thin film) 2958,1594,1448,1249,853,767,705 cm"1; MS, m/z (relative intensity) 558 (M+, 96), 485 (15), 439 (58), 338 (100), 214 (30), 203 (13), 138 (10), 124 (11), 119 (17), 57 (14); HRMS caled for QaH^CoOSi, 558.2728, found 558.2734; NMR (300 MHz, CA) 6.95-7.15 (m, 5 H), 4.82 (br s, 1 H), 3.75 (br s, 1 H), 3.69 (br s, 1 H), 3.62 (br s, 1 H), 3.06 (br dd, J = 13.3, 2.3 Hz, 1 H), 2.26 (ddd, J = 9.9, 9.7, 2.2 Hz, 1 ), 2.17 (ddd, J = 16.6, 7.3, 6.5 Hz, 1 ), 1.82-2.05 (m, 2 ), 1.72-1.82 (m, 4 ), 1.69 (m, 1 H), 1.50-1.62 (m, 3 ), 1.45 (s, 3 ), 1.36 (d, J = 6.4 Hz, 3 ), 1.30-1.40 (m, 3 ), 1.14 (m, 1 ), 1.12 (s, 3 ), 1.06 (s, 3 ), 0.44 (s, 9 H); 13C NMR (75.5 MHz, CA) 166.2,151.9,128.0,126.9,124.9,110.1, 94.2, 93.4, 81.3, 81.2, 80.2, 78.0, 74.8, 61.1, 55.1, 42.6, 40.8, 40.1, 36.4, 34.2, 29.8, 28.4, 25.5, 25.2, 23.4, 22.9, 22.7, 22.1, 9.3, 0.3. The second fraction contained the major isomer (0.037 g), also as a red oil: IR (thin film) 2960,1594,1451,1248,853,839,767,707 cm"1; MS, m/z (relative intensity) 558 (M+, 100), 485 (13), 439 (50), 338 (76), 214 (19), 119 (19), 109 (27), 105 (13), 83 (39), 71 (48.3), 57 (81); HRMS caled for C^H^CoOSi, 558.2728, found 558.2732; XH NMR (300 MHz, CA) 6.95-7.15 (m, 5 ), 4.60 (br s, 1 H), 3.83 (br s, 1 H), 3.44 (br s, 2 H), 3.18 (br dd, J = 12.9, 2.3 Hz, 1 H), 2.55 (ddd, J = 9.9, 9.7, 2.4 Hz, 1 ), 2.18 (ddd, J = 16.8, 7.2, 6.5 Hz, 1 ), 1.80-2.00 (m, 3 ), 1....…”