Synlett 2005(10): 1543-1546  
DOI: 10.1055/s-2005-869845
LETTER
© Georg Thieme Verlag Stuttgart · New York

Intramolecular Pauson-Khand Reactions of Cycloheptynedicobalt Complexes

Ahmed B. Mohamed, James R. Green*, Jason Masuda
Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
Fax: +1(519)9737098; e-Mail: jgreen@uwindsor.ca;
Further Information

Publication History

Received 8 April 2005
Publication Date:
12 May 2005 (online)

Abstract

Cycloheptyne-Co2(CO)6 complexes bearing alkenes tethered by oxygen, sulfur, and nitrogen atoms undergo Pauson-Khand reactions to afford tricyclic compounds containing a fused 7,5-ring system.

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Selected compounds.
Compound 2c: IR (neat, NaCl): νmax = 2932, 2090, 2047, 2020 cm-1. 1 H NMR: δ = 5.98 (m, 1 H), 5.34 (dd, J = 17.1, 1.5 Hz, 1 H), 5.21 (dd, J = 10.4, 1.5 Hz, 1 H), 4.48 (dd, J = 10.4, 4.2 Hz, 1 H), 4.35 (dd, J = 12.5, 5.1 Hz, 1 H), 4.19 (dd, J = 12.5, 5.7 Hz, 1 H), 3.19 (apparent dt, J = 16.7, 3.4 Hz, 1 H), 2.76 (m, 1 H), 2.19 (m, 1 H), 2.05 (m, 1 H), 1.97 (m, 1 H), 1.48-1.65 (m, 2 H), 1.39 (m, 1 H). 13C NMR: δ = 203.9, 138.7, 121.0, 103.6, 102.5, 84.4, 74.2, 40.9, 39.4, 33.1, 29.7. MS: m/e = 380 [M - 2 CO+]. HRMS: m/e calcd for C16H14Co2O7 [M - 2 CO+]: 379.9500; found: 379.9466.
Compound 2e: IR (neat, NaCl): νmax = 2927, 2089, 2049, 2020 cm-1. 1H NMR: δ = 5.88 (m, 1 H), 5.15 (d, J = 17.7 Hz, 1 H), 5.12 (d, J = 12.0 Hz, 1 H), 3.89 (dd, J = 14.2, 4.2 Hz, 1 H), 3.29 (d, J = 7.5 Hz, 2 H), 3.12 (dt, J = 16.3, 3.6 Hz, 1 H), 2.82 (m, 1 H), 2.27 (m, 1 H), 2.11 (m, 1 H), 1.95 (m, 1 H), 1.68 (m, 1 H), 1.59 (m, 1 H), 1.45 (m, 1 H). 13C NMR: δ = 200.0, 134.7, 116.9, 102.0, 99.9. 48.5, 38.0, 35.5, 35.0, 29.8, 28.8. MS: m/e = 424 [M - CO+], 396 [M - 2 CO+]. HRMS: m/e calcd for C16H14Co2O6S [M - 2 CO+]: 395.9271; found: 395.9295.
Compound 2i: IR (neat, KBr): νmax = 3082, 2928, 2093, 2051, 2025 cm-1. 1H NMR: δ = 7.72 (d, J = 8.3 Hz, 2 H), 7.28 (d, J = 8.3 Hz, 2 H), 5.76 (m, 1 H), 5.20 (dd, J = 17.2, 1.3 Hz, 1 H), 5.07 (dd, J = 10.2, 1.3 Hz, 1 H), 4.96 (dd, J = 11.7, 3.2 Hz, 1 H), 4.14-4.26 (m, 2 H), 3.23 (br d, J = 13.5 Hz, 1 H), 2.73 (m, 1 H), 2.43 (s, 3 H), 2.11 (m, 1 H), 1.92-2.04 (m, 2 H), 1.73 (m, 1 H), 1.35-1.60 (m, 2 H). 13C NMR: δ = 199.1, 143.1, 138.6, 135.8, 129.5, 127.3, 117.3, 102.2, 96.9, 63.5, 46.2, 37.0, 35.6, 28.9, 21.5. MS: m/e = 533 [M - 2 CO+], 505 [M - 3 CO+], 421 [M - 6 CO+]. HRMS: m/e calcd for C23H21Co2NO8S [M - 3 CO+]: 504.9804; found: 504.9828.

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Experimental Procedure.
A solution of 2b (73.0 mg, 0.16 mmol) and 3.5 equiv of cyclohexylamine (3.5 equiv, 64 µL) in 1,2-dichloroethane (8 mL) was heated to reflux for 20 min. The solution was cooled to r.t., 20 mL Et2O (20 mL) was added, and the mixture was filtered through a pad of silica gel. Preparative TLC (4:1 petroleum ether-Et2O) of the crude material afforded 5b (20.2 mg, 65% yield, 3.8:1 cis:trans).

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Compound 5a: IR (neat, NaCl): νmax = 3079, 2957, 1737, 1715 cm-1. 1 H NMR: δ = 5.84 (m, 1 H), 5.80 (m, 1 H), 4.69 (br d, J = 10.9 Hz, 1 H), 4.28 (apparent t, J = 7.1 Hz, 1 H), 3.31 (m, 1 H), 3.29 (d, J = 7.1 Hz, 1 H), 2.95-3.08 (m, 2 H), 2.63-2.71 (m, 2 H), 2.23 (m, 1 H), 2.16 (dd, J = 18.5, 2.7 Hz, 1 H); resonances for the minor diastereomer were observed at δ = 4.72 (apparent t, J = 6.0 Hz, 1 H), 4.38 (apparent t, J = 7.4 Hz, 1 H), 3.46 (dd, J = 10.9, 8.7 Hz, 1 H), 2.11 (J = 18.0, 2.7 Hz, 1 H). 13C NMR: δ = 208.1, 179.9, 128.7, 125.3, 72.9, 70.5, 43.2, 38.8, 33.3, 29.7, 25.1. MS: m/e = 176 [M+]. HRMS: m/e calcd for C11H12O2 [M+]: 176.0837; found: 176.0842
Compound 5b: IR (neat, NaCl): νmax = 3012, 2922, 1709, 1678 cm-1. 1 H NMR: δ = 5.59 (ddd, J = 12.4, 7.2, 2.1 Hz, 1 H), 5.61 (m, 1 H), 4.48 (br d, J = 12.0 Hz, 1 H), 3.37 (m, 1 H), 3.13 (dd, J = 10.9, 6.7 Hz, 1 H), 3.07 (m, 1 H), 2.95 (m, 1 H), 2.73 (1/2 ABquartet, J = 6.3 Hz, 1 H), 2.70 (1/2 ABquartet, J = 6.3 Hz, 1 H), 2.57 (m, 1 H), 2.43 (m, 1 H), 2.22 (dd, J = 17.1, 4.1 Hz, 1 H); resonances for the minor diastereomer were observed at δ = 4.20 (br d, J = 4.20 Hz, 1 H), 2.66 (d, J = 6.5 Hz, 1 H), 2.18 (obscured dd, 1 H). 13C NMR: δ = 207.0, 183.4, 135.2, 126.6, 126.1, 47.9, 44.9, 42.6, 37.1, 32.3, 23.8; resonances for the minor diastereomer were observed at δ = 129.2, 47.0, 43.2, 40.3. MS: m/e = 192 [M+]. HRMS: m/e for C11H14O2S [M+]: 192.0603; found: 192.0580.
Compound 5c: IR (neat, NaCl): νmax = 2927, 1714, 1680 cm-1. 1H NMR: δ = 4.74 (dd, J = 10.9, 5.7 Hz, 1 H), 4.27 (apparent t, J = 7.7 Hz, 1 H), 3.36 (dd, J = 11.3, 7.7 Hz, 1 H), 3.27 (m, 1 H), 2.64 (dd, J = 17.7, 6.3 Hz, 1 H), 2.58 (m, 1 H), 2.21 (m, 1 H), 2.14 (dd, J = 17.6, 3.1 Hz, 1 H), 2.09 (m, 1 H), 1.99 (m, 1 H), 1.93 (m, 1 H), 1.56 (m, 1 H), 1.30-1.49 (m, 2 H); resonances for the minor diastereomer were observed at δ = 4.35 (obscured m, 1 H), 4.32 (apparent t, J = 7.8 Hz, 1 H), 3.35 (dd, J = 11.4, 8.3 Hz, 1 H), 2.26 (dd, J = 16.6, 4.7 Hz, 1 H), 2.55 (obscured m, 1 H). 13C NMR: δ = 208.4, 186.0, 137.7, 79.6, 71.9, 44.8, 41.0, 34.0, 27.6, 26.5, 23.5; resonances for the minor diastereomer were observed at δ = 206.8, 182.2, 135.4, 77.1, 71.4, 43.6, 39.0, 29.5, 27.5, 24.6, 23.4. MS: m/e = 178 [M+], 150 [M - CO+]. HRMS: m/e calcd for C11H14O2 [M - CO+] 150.1045; found: 150.1038.
Compound 5d: IR (neat, NaCl): νmax = 2928, 1713, 1677 cm-1. 1H NMR: δ = 4.79 (ddd, J = 10.9, 5.7, 1.6 Hz, 1 H), 3.93 (d, J = 8.0 Hz, 1 H), 3.54 (d, J = 8.0 Hz, 1 H), 2.55 (apparent dt, J = 16.1, 4.2 Hz, 1 H), 2.39 (1/2 ABquartet, J = 17.1 Hz, 1 H), 2.35 (1/2 ABquartet, J = 17.1 Hz, 1 H), 2.21 (m, 1 H), 2.05 (m, 1 H), 1.98 (m, 1 H), 1.90 (m, 1 H), 1.55 (m, 1 H), 1.40 (m, 1 H), 1.33 (m, 1 H), 1.31 (s, 3 H). 13C NMR: δ = 208.1, 185.7, 136.2, 76.1, 48.6, 47.4, 33.8, 27.5, 24.9, 24.5, 23.4. MS: m/e = 192 [M+]. HRMS: m/e calcd for C12H16O2 [M+]: 192.1150; found: 192.1143.
Compound 5e: IR (neat, NaCl): νmax = 2928, 1703, 1665 cm-1. 1H NMR: δ = 4.14 (br d, J = 11.6 Hz, 1 H), 3.31 (m, 1 H), 3.04 (dd, J = 10.6, 6.7 Hz, 1 H), 2.69 (dd, J = 17.0, 6.0 Hz, 1 H), 2.65 (m, 1 H), 2.60 (apparent t, J = 11.3 Hz, 1 H), 2.18 (dd, J = 16.8, 4.3 Hz, 1 H), 2.04 (m, 1 H), 1.85-1.97 (m, 2 H), 1.53 (m, 2 H), 1.47 (m, 1 H), 1.14 (m, 1 H); resonances for the minor diastereomer were observed at δ = 4.19 (br d, J = 11.3 Hz, 1 H), 2.65 (J = 18.5, 6.2 Hz, 1 H), 2.58 (m, 1 H), 2.23 (m, 1 H), 1.41 (m, 1 H). 13C NMR: δ = 207.4, 184.9, 139.0, 48.5, 42.6, 36.1, 31.2, 30.9, 27.0, 23.0; resonances for the minor diastereomer were observed at δ = 208.1, 181.0, 139.5, 48.2, 46.8, 41.2, 37.4, 35.3, 28.5, 23.5. MS: m/e = 194 [M+]. HRMS (ESI): m/e calcd for C11H14OS [M + Na+]: 217.0658; found: 217.0650.
Compound 5f: IR (neat, NaCl): νmax = 2928, 1702, 1648 cm-1. 1H NMR: δ = 4.23 (dd, J = 9.9, 4.2 Hz, 1 H), 4.06 (m, 1 H), 3.66 (apparent dt, J = 2.1, 11.9 Hz, 1 H), 2.77 (m, 1 H), 2.62 (dd, J = 18.7, 6.3 Hz, 1 H), 2.26-2.28 (2 H), 1.97-2.15 (m, 3 H), 1.81-1.91 (m, 2 H), 1.28-1.75 (m, 4 H); resonances for the minor diastereomer were observed at δ = 4.26 (br d, obscured, 1 H), 4.09 (m, 1 H), 3.74 (ddd, J = 11.4, 9.3, 4.6 Hz, 1 H), 3.01 (m, 1 H), 2.70 (m, 1 H), 2.67 (dd, J = 18.2, 6.3 Hz, 1 H), 2.70 (m, 1 H), 1.41 (m, 1 H), 1.14 (m, 1 H). 13C NMR: δ = 207.5, 170.4, 139.2, 78.6, 66.8, 41.0, 37.8, 34.0, 32.2, 25.9, 22.3, 21.3; resonances for the minor diastereomer were observed at δ = 206.5, 179.3, 137.5, 63.6, 41.1, 32.3, 31.9, 28.2, 27.5, 26.6. MS: m/e = 192 [M+]. HRMS (ESI): m/e calcd for C11H14O2 [M + Na+]: 215.1048; found: 215.1050.
Compound 5i: IR (neat, NaCl): νmax = 2923, 1714, 1680 cm-1. 1H NMR: δ = 7.78 (d, J = 8.2 Hz, 2 H) and 7.72 (d, J = 8.2 Hz, 2 H), 7.34 (d, J = 8.2 Hz, 2 H) and 7.38 (d, J = 8.2 Hz, 2 H), 4.46 (ddd, J = 10.9, 5.4, 1.5 Hz, 1 H), 4.00 (dd, J = 12.0, 7.8 Hz, 1 H), 3.96 (apparent t, J = 7.8 Hz, 1 H), 3.57 (br d, J = 9.8 Hz, 1 H), 3.12 (m, 1 H), 2.94 (apparent t, J = 11.5 Hz, 1 H), 2.73 (m, 1 H), 2.62 (dd, J = 16.9, 6.0 Hz, 1 H), 2.50-2.54 (m, 3 H), 2.43 (s, 3 H) and 2.45 (s, 3 H), 2.39-2.50 (m, 3 H), 2.18 (m, 1 H), 1.96-2.10 (m, 4 H), 1.79-1.93 (m, 2 H), 1.43-1.64 (m, 4 H), 1.24-1.39 (m, 2 H), 1.13 (m, 1 H). 13C NMR: δ = 207.2, 205.4, 180.9, 178.5, 144.3, 143.8, 139.2, 137.7, 136.0, 131.7, 130.0, 129.9, 128.0, 127.1, 62.6, 61.4, 54.2, 52.7, 41.6, 40.9, 40.4, 39.3, 35.7, 30.9, 30.3, 28.1, 27.1, 27.0, 25.9, 23.5, 22.8, 21.6. MS:
m/e = 194 [M+]. MS: m/e 331 (M+); HRMS m/e calcd for C18H21NO3S [M+]: 331.1242; found: 331.1237.