Methyl Metallocenecarboxylates and Their Desilylation Reactions
CpH), 5.14 (s, 2 H, CpH), 6.97 (m, 6 H, PhH), 7.03 (m, 4 H, PhH),
FULL PAPER
902 s, 817 s, 764 vs, 691 vs. 663 m, 538 m, 480 s cm–1. MS (FAB):
0.01 (SiMe3) ppm. 13C NMR (75 MHz, CDCl3): δ = 0.8 (SiMe3C), m/z = 386 [M+], 387[M+ + 1], 355 [M+ – OCH3], 263 [M+
–
51.0 (COOMeC), 67.9, 82.0 (C4 ring), 82.7, 87.1, 90.4 (CpC), 126.4,
CpCO2Me]. C23H19CoO2 (386.07): calcd. C 71.51, H 4.96; found
127.5, 129.0, 135.7 (PhC), 166.2 (C=O) ppm. IR, (KBr): ν = C 71.63, H 4.92.
˜
3054 m, 3021 w, 2954 s, 2896 m, 1710 vs, 1599 w, 1467 vs, 1439 s,
[{cis-η4-Ph2H2C4}Co{η5-MeOC(O)C5H4}] (6): Chromatographed
on silica gel with hexane as eluent to give 0.35 g (92%) of 6. M.p.
70 °C. H NMR (300 MHz, CDCl3): δ = 3.36 (s, 3 H, CH3), 4.88
1369 s, 1287 vs, 1248 vs, 1192 s, 1147 vs, 1064 m, 1028 m, 970 m,
839 vs, 772 vs, 695 vs, 633 w, 616 w, 509 w cm–1. MS (FAB): m/z =
530 [M+], 531 [M+ + 1], 529 [M+ – 1], 498 [M+ – OCH3], 514
1
(s, 2 H, CpH), 5.24 (s, 2 H, CpH), 4.46 (s, 2 H, C4 ring), 7.24–7.26
(m, 6 H, PhH), 7.38 (m, 4 H, PhH) ppm. 13C NMR (75 MHz,
CDCl3): δ = 51.22 (CH3), 58.2, 77.4 (C4 ring), 82.6 (CpC), 83.1,
86.2 (CpC), 124.6, 126.6, 128.3, 136.7 (PhC), 167.2 (C=O) ppm. IR
(KBr): 3059 m, 29469 m, 1706 vs, 1597 w, 1567 w, 1499 w, 1458 s,
1359 m, 1278 vs, 1187 m, 1135 vs, 1024 w, 961 m, 893 m, 827 m,
766 vs, 694 vs, 576 vs, 523 m cm–1. MS (FAB): m/z = 386 [M+], 387
[M+ + 1], 355 [M+ – OCH3], 263 [M+ – CpCO2Me]. C23H19CoO2
(386.07): calcd. C 71.51, H 4.96; found C 71.58, H 4.85.
[M+ – CH3], 457 [M+ – SiMe3], 356 [M+ – PhCCSiMe3], 407 [M+
–
CpCO2Me]. C29H35CoO2Si2 (530.15): calcd. C 65.63, H 6.65; found
C 65.57, H 6.60.
Preparation of [{η4-Ph3(Me3Si)C4}Co{η5-MeOC(O)C5H4}] (3) and
[(η4-Ph4C4)Co{η5-MeOC(O)C5H4}] (4): A solution of chloridotris-
(triphenylphosphane)cobalt(I) (5.16 g, 5.84 mmol) in toluene
(30 mL) was added to a solution of [(methoxycarbonyl)cyclopen-
tadienyl]sodium (0.86 g, 5.85 mmol) in thf (5 mL). The resulting
red solution was stirred at room temperature for 0.5 h and then a
solution of (2-phenylethynyl)trimethylsilane (0.61 g, 3.50 mmol) in
toluene was added and stirred at room temperature for 1 h to give
[(η4-Ph3HC4)Co{η5-MeOC(O)C5H4}] (7): Chromatographed on
silica gel with hexane as eluent to give 0.33 g (87%) of 7. M.p.
1
180 °C. H NMR (300 MHz, CDCl3): δ = 3.21 (s, 3 H, CH3), 4.67
a
brown solution. A solution of diphenylacetylene (1.04 g,
(s, 2 H, CpH), 5.02 (s, 1 H, C4 ring), 5.33 (s, 2 H, CpH), 7.7 (m, 2
H, PhH), 7.34 (m, 3 H, PhH), 7.24–7.18 (m, 10 H, PhH) ppm. 13C
NMR (75 MHz, CDCl3): δ = 51.1 (CH3C), 54.6, 76.1, 77.9 (C4
ring), 85.7, 84.9, 82.9 (CpC), 125.9, 126.3, 127.0, 128.1, 128.3,
130.1, 135.4, 136.2 (PhC), 166.2 (C=O) ppm. IR (KBr): 3080 w,
2948 w, 2362 w, 1714 vs, 1595 m, 1500 s, 1467 s, 1363 m, 1281 vs,
1187 s, 1139 vs, 1067 w, 1026 w, 967 w, 825 w, 764 vs, 692 vs, 608 w,
5.85 mmol) in toluene was added and the resulting mixture was
stirred at room temperature for 10 min and thereafter refluxed for
8 h and cooled to room temperature. The solvent was removed in
vacuo and the residue suspended in 20% ethyl acetate in hexane
and filtered. The filtrate was concentrated and chromatographed
on silica gel, eluting with a hexane/ethyl acetate mixture (2% ethyl
acetate) to give a yellow solution, which upon slow cooling gave
crystals of 3 (0.52 g, 29%). On increasing the polarity of the eluent
(10% ethyl acetate) a dark yellow solution was obtained, which on
cooling gave crystals of 4 (0.76 g, 24%). The physical and spectral
properties of 4 were found to agree well with those reported in the
literature.[9]
582 w cm–1. MS (FAB): m/z = 462 [M+], 463 [M+ + 1], 339 [M+
–
CpCO2Me]. C29H23CoO2 (462.40): calcd. C 75.32, H 5.01; found
C 75.24, H 5.15.
General Procedure for the De-esterification of Compounds 5–7: A
mixture of 1.0 mmol of the ester and potassium tert-butoxide
(1.68 g, 15 mmol) in 10 mL of dmso was stirred at room tempera-
[{η4-Ph3(Me3Si)C4}Co{η5-MeOC(O)C5H4}] (3): M.p. 75 °C. 1H ture for 15 h and then quenched with 2 HCl (20 mL). After ex-
NMR (300 MHz, CDCl3): δ = 0.27 (s, 9 H, SiMe3), 3.33 (s, 3 H, traction with ethyl acetate, the organic phase was separated and
CH3), 4.94 (s, 2 H, CpH), 5.37 (s, 2 H, CpH), 7.28–7.34 (m, 9 H, dried with MgSO4. The solvent was removed in vacuo and the resi-
PhH), 7.47–7.48 (m, 6 H, PhH) ppm. 13C NMR (75 MHz, CDCl3): due was column-chromatographed on silica gel with an appropriate
δ = 1.1 (SiMe3), 51.1 (CO2Me), 63.1, 82.5 (C4 ring), 83.6, 84.3, 86.9 eluent to give the carboxylic acid complex.
(CpC), 135.9, 135.1, 129.6, 129.0, 128.0, 127.7, 126.7, 126.5 (PhC),
[trans-(η4-Ph2H2C4)Co(η5-C5H4COOH)] (8): Chromatographed on
167.2 (C=O) ppm. IR (KBr): ν = 3051 m, 3020 w, 2950 m, 1717 vs,
˜
silica gel with 20% EtOAc/chloroform as eluent to give 0.31 g
1596 m, 1495 m, 1469 m, 1444 m, 1364 m, 1280 vs, 1250 s, 1229 m,
1145 s, 1066 w, 826 s, 768 s, 694 s, 585 s cm–1. MS (FAB): m/z = 534
[M+], 335 [M+ + 1], 356 [M+ – PhCCPh], 411 [M+ – CpCO2Me],
360 [M+ – PhCCSiMe3], 503 [M+ – OCH3]. C32H31CoO2Si
(534.14): calcd. C 71.89, H 5.84; found C 71.80, H 5.90.
1
(84%) of 8 as an orange crystalline solid. M.p. 165 °C. H NMR
(300 MHz, CDCl3): δ = 4.75 (br. s, 2 H, CpH), 5.06 (s, 2 H, C4
ring), 5.40 (br. s, 2 H, CpH), 7.10–7.20 (m, 10 H, PhH) ppm. 13C
NMR (75 MHz, CDCl3): δ = 54.2, 76.1 (C4 ring), 85.3, 86.8, 92.5
(CpC), 124.8, 126.2, 128.6, 135.9 (PhC), 193.1 (COOH) ppm. IR
(KBr): ν = 3053 m, 3023 m, 2912 m, 1659 vs, 1596 m, 1495 m,
˜
General Procedure for the Desilylation of Compounds 1–3: The sil-
ylated cobalt complex (1.0 mmol) and a slight excess of tetrabu-
tylammonium fluoride (1 solution in thf) were dissolved in dmso
(10 mL) and the mixture was stirred at 70 °C under nitrogen for
24 h. The product was extracted with ethyl acetate, and the solution
was washed repeatedly with water to remove any trace of dmso.
The ethyl acetate solution was dried with anhydrous MgSO4 and
concentrated to give a dark yellow powder, which was chromato-
graphed on silica gel with an appropriate eluent.
1448 s, 1365 m, 1296 m, 1184 w, 1118 w, 1034 vs, 966 s, 758 vs,
695 vs, 541 s cm–1. MS (FAB): m/z = 371 [M+ – 1], 370 [M+ – 2],
369 [M+ – 3], 263 [M+ – CpCO2Me]. C22H17CoO2 (372.05): calcd.
C 70.97, H 4.60; found C 71.05, H 4.65.
[cis-(η4-Ph2H2C4)Co(η5-C5H4COOH)] (9): Chromatographed on
silica gel with 20% EtOAc/chloroform as eluent to give 0.29 g
1
(78%) of 9 as an orange crystalline solid. M.p. 188 °C. H NMR
(300 MHz, CDCl3): δ = 4.48 (s, 2 H, C4 ring), 4.75 (s, 2 H, CpH),
5.18 (s, 2 H, CpH), 7.21–7.33 (s, 10 H, PhH) ppm. 13C NMR
(75 MHz, CDCl3): δ = 58.3, 77.4 (C4 ring), 86.4, 87.1, 92.2 (CpC),
[{trans-η4-Ph2H2C4}Co{η5-MeOC(O)C5H4}]
(5):
Chromato-
graphed on silica gel with hexane as eluent to give 0.36 g (93%) of
5. M.p. 122 °C. 1H NMR (300 MHz, CDCl3): δ = 3.20 (s, 3 H,
CH3), 4.96 (s, 2 H, C4 ring), 4.60 (s, 2 H, CpH), 5.39 (s, 2 H, CpH),
7.19 (m, 6 H, PhH), 7.17 (m, 4 H, PhH) ppm. 13C NMR (75 MHz,
CDCl3): δ = 51.1 (OMeC), 54.8, 76.1 (C4 ring), 81.7, 84.1, 86.1
(CpC), 124.5, 126.1, 128.4, 136.3 (PhC), 166.7 (C=O) ppm. IR
126.2, 128.1, 128.6, 136.2 (PhC), 192.2 (COOH) ppm. IR (KBr): ν
˜
= 2927 w, 2625 w, 1674 vs, 1599 m,1480 w, 1421 m, 1354 w, 1295 vs,
1165 w, 1122 w, 1021 w, 947 m, 761 s, 694 s cm–1. MS (ESI): m/z =
371 [M+ – 1], 325 [M+ – COOH]. C22H17CoO2 (372.30): calcd. C
70.97, H 4.60; found C 71.07, H 4.69.
(KBr): ν = 3086 w, 3055 m, 2952 m, 1708 vs, 1594 s, 1501 s, 1468 vs, [(η4-Ph3HC4)Co(η5-C5H4COOH)] (10): Chromatographed on sil-
˜
1393 m 1358 m, 1282 vs, 1197 s, 1143 vs, 1067 m, 1022 s, 967 s, ica gel with 20% EtOAc/chloroform as eluent to give 0.38 g (85%)
Eur. J. Inorg. Chem. 2006, 5022–5032
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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