Benzocycloheptynedicobalt Complexes by Intramolecular Nicholas Reactions

Abstract

Lewis acid mediated intramolecular Nicholas reactions of aryl (Z)-enyne propargyl acetate-Co₂(CO)₆ complexes 1 afford benzocycloheptenyne-Co₂(CO)₆ complexes 2 and their heterocyclic analogues.

Nicholas reactions - alkynes - arenes - complexes - transition metals

References

For recent reviews, see:

1a Green JR. Curr. Org. Chem.  2001,  5:  809 

1b Teobald BJ. Tetrahedron  2002,  58:  4133 

2a Lu Y. Green JR. Synlett  2001,  243 

2b Patel MM. Green JR. Chem. Commun.  1999,  509 

2c Green JR. Chem. Commun.  1998,  1751 

3a Tanino K. Onuki K. Asano K. Miyashita M. Nakamura T. Takahashi Y. Kuwajima I. J. Am. Chem. Soc.  2003,  125:  1498 

3b Tanino K. Kondo F. Shimizu T. Miyashita M. Org. Lett.  2002,  4:  2217 

3c Tanino K. Shimizu T. Miyama M. Kuwajima I. J. Am. Chem. Soc.  2000,  122:  6116 

3d Schreiber SL. Sammakia T. Crowe WE. J. Am. Chem. Soc.  1986,  108:  3128 

4a Young DGJ. Burlison JA. Peters U. J. Org. Chem.  2003,  68:  3494 

4b Green JR. Synlett  2001,  353 

4c Iwasawa N. Sakurada F. Iwamoto M. Org. Lett.  2000,  2:  871 

5 Iwasawa N. Satoh H. J. Am. Chem. Soc.  1999,  121:  7951 

For examples, see:

6a Uchiyama N. Kiuchi F. Ito M. Honda G. Takeda Y. Khodzhimatov OK. Ashurmetov OA. J. Nat. Prod.  2003,  66:  128 

6b Ulubelen A. Topcu G. J. Nat. Prod.  2000,  63:  879 

For examples, see:

7a Ulubelen A. Topcu G. Tan N. Lin L.-J. Cordell GA. Phytochemistry  1992,  31:  2419 

7b Purushothaman KK. Chandrasekharan S. Cameron AF. Connolly JD. Labbe C. Maltz A. Rycroft DS. Tetrahedron Lett.  1979,  979 

7c Lee J. Hong J. J. Org. Chem.  2004,  69:  6433 

8 Bentley KW. Nat. Prod. Rep.  2004,  21:  395 ; and references therein

For examples, see:

9a Ho T.-L. Lin Y.-J. J. Chem. Soc., Perkin Trans. 1  1999,  1207 

9b Inoue M. Carson MW. Frontier AJ. Danishefsky SJ. J. Am. Chem. Soc.  2001,  123:  1878 

9c Asakawa Y. Toyota M. Tsunematsu T. Kubo I. Nakanishi K. Phytochemistry  1980,  19:  2147 

10 Ramirez F. Desai NB. McKelvie N. J. Am. Chem. Soc.  1962,  84:  1745 

11 Uenishi J. Kawahama R. Yonemitsu O. Tsuji J. J. Org. Chem.  1996,  63:  8965 

12

Selected compounds:
Compound 5b: IR (neat, KBr): ν_max = 3345, 3020, 2920, 2193 cm^-1. ¹H NMR: δ = 1.77 (1 H, br), 2.38 (3 H, s), 4.50 (1 H, d, J = 2.0 Hz), 5.71 (1 H, dt, J = 11.9, 2.0 Hz), 6.64 (1 H, d, J = 11.9 Hz), 7.11 (1 H, d, J = 7.5 Hz), 7.27 (1 H, dd, J = 7.7, 7.5 Hz), 7.63 (1 H, s), 7.68 (1 H, d, J = 7.7 Hz). ¹³C NMR: δ = 139.4, 137.8, 136.1, 129.4, 128.2, 125.6, 106.5, 93.6, 84.3, 51.8, 21.4. MS (EI): m/z = 172. HRMS (EI): m/z calcd for C₁₂H₁₂O: 172.0888; found: 172.0888.
Compound 5g: IR (neat, KBr): ν_max = 3358, 3097, 2918, 2191, 1699, 1602 cm^-1. ¹H NMR: δ = 2.39 (1 H, s), 4.51 (2 H, d, J = 2.0 Hz), 5.62 (1 H, dt, J = 11.7, 2.3 Hz), 6.70 (1 H, d, J = 11.7 Hz), 7.29 (1 H, dd, J = 4.9, 2.6 Hz), 7.62 (1 H, d, J = 5.0 Hz), 7.76 (1 H, d, J = 2.1 Hz). ¹³C NMR: δ = 138.3, 133.0, 127.7, 125.6, 125.2, 105.2, 93.8, 84.4, 51.6. MS (EI): m/z = 164. HRMS (EI): m/z calcd for C₉H₈OS: 164.0296; found: 164.0292.

13

Selected compounds:
Compound 1b: IR (neat, KBr): ν_max = 3014, 2927, 2092, 2024, 1748 cm^-1. ¹H NMR: δ = 2.03 (3 H, s), 2.39 (3 H, s), 4.52 (2 H, s), 6.61 (1 H, d, J = 11.0 Hz), 6.80 (1 H, d, J = 11.0 Hz), 7.02 (2 H, d, J = 8.2 Hz), 7.14 (1 H, d, J = 7.6 Hz), 7.29 (1 H, d, J = 7.5 Hz). ¹³C NMR: δ = 199.1 (br), 170.5, 138.2, 137.6, 132.5, 129.0, 128.5, 128.4, 127.5, 125.4, 91.4, 83.5, 64.9, 21.3, 20.3. MS (EI): m/z = 472 [M - CO]⁺, 444 [M - 2 CO]⁺, 416 [M -3 CO]⁺, 388 [M - 4 CO]⁺, 360 [M - 5 CO]⁺, 332 [M - 6CO]⁺. HRMS (EI): m/z calcd for C₂₀H₁₄ Co₂O₈: 443.9454 [M - 2 CO]⁺; found: 443.9457.
Compound 1g: IR (neat, KBr): ν_max = 3013, 2956, 2092, 2022, 1746 cm^-1. ¹H NMR: δ = 2.07 (3 H, s), 4.73 (2 H, s), 6.62 (1 H, d, J = 11.0 Hz), 6.67 (1 H, d, J = 11.0 Hz), 6.98 (1 H, d, J = 4.3 Hz), 7.13 (1 H, s), 7.38 (1 H, s). ¹³C NMR: δ = 199.3 (br), 170.5, 138.2, 128.3, 128.2, 126.8, 126.2, 123.4, 91.4, 83.3, 64.5, 20.3. MS (EI): m/z = 464 [M - CO]⁺, 436 [M - 2 CO]⁺, 408 [M - 3 CO]⁺, 380 [M - 4 CO]⁺, 352 [M - 5 CO]⁺, 324 [M - 6 CO]⁺. HRMS (EI): m/z calcd for C₁₇H₁₀Co₂O₈S: 435.8862 [M - 2 CO]⁺; found: 435.8853.

14

Experimental Procedure:
To a stirred ice cold solution of the propargyl acetate complex (0.2 mmol) in CH₂Cl₂ (20 mL) was added BF₃·OEt₂ (85.2 mg, 0.60 mmol) in CH₂Cl₂ (4 mL) over 10 min. After stirring at 0 °C for the time indicated in Table [2] , sat. NaHCO₃ solution was added, and the mixture was subjected to a conventional work up. Purification by flash chroma-tography afforded sequentially the benzocycloheptenyne complex and any recovered starting material.

15 This reflects a tendency for a slightly lower preference for C-2 reactivity in thiophenes relative to furans and perhaps the known tendency for electron withdrawing C-3 groups to deactivate C-2 to a greater degree than C-4. See: Taylor R. In The Chemistry of Heterocyclic Compounds   Part 2, Vol. 44:  Gronowitz S. Wiley; New York: 1986.  Chap. 1. p.16 

16 Brook MA. Silicon in Organic, Organometallic, and Polymer Chemistry   Wiley and Sons; New York: 2000. 

17

Compound 2a: IR (neat, KBr): ν_max = 2929, 2091, 2021, 1574 cm^-1. ¹H NMR: δ = 4.18 (2 H, s), 6.77 (1 H, d, J = 10.1 Hz), 6.93 (1 H, d, J = 10.1 Hz), 7.22 (4 H, m). ¹³C NMR: δ = 199.3 (br), 137.5, 137.3, 133.1, 132.5, 129.4, 128.9, 128.8, 126.9, 102.3, 86.5, 40.8. MS (EI): m/z = 426 [M]⁺, 398 [M - CO]⁺, 370 [M - 2 CO]⁺, 342 [M - 3 CO]⁺, 314 [M - 4 CO]⁺, 286 [M - 5 CO]⁺, 258 [M - 6 CO]⁺. HRMS (EI): m/z calcd for C₁₇H₈Co₂O₆: 426.9063 [M + H]⁺; found: 426.9069.
Compound 2b: IR (neat, KBr): ν_max = 3014, 2858, 2090, 2053, 2021, 1557 cm^-1. ¹H NMR: δ = 2.31 (3 H, s), 4.14 (2 H, s), 6.72 (1 H, d, J = 10.1 Hz), 6.90 (1 H, d, J = 10.1 Hz), 7.00 (1 H, s), 7.07 (1 H, d, J = 7.9 Hz), 7.15 (1 H, d, J = 7.6 Hz); resonances for minor regioisomer (2b′) could be observed at δ = 2.51 (3 H, s), 4.10 (2 H, s), 6.82 (1 H, d, J = 10.0 Hz), 6.93 (1 H, d, J = 10.0 Hz), 7.03 (1 H, m), 7.10 (1 H, m), 7.17 (1 H, m). ¹³C NMR: δ = 199.4 (br), 137.3, 136.4, 134.5, 133.2, 129.6, 129.4, 128.5, 102.5, 86.9, 40.4, 20.7; resonances for the minor regioisomer could be observed at δ = 133.8, 130.7, 130.4, 128.8, 126.3, 34.2, 21.1. MS (EI): m/z = 440 [M]⁺, 412 [M - CO]⁺, 384 [M - 2 CO]⁺, 356 [M⁺ - 3 CO], 328 [M - 4 CO]⁺, 300 [M - 5 CO]⁺, 272 [M - 6 CO]⁺. HRMS (EI): m/z calcd for C₁₈H₁₀Co₂O₆: 439.9141; found: 439.9137.
Compound 2c: IR (neat, KBr): ν_max = 3014, 2956, 2837, 2090, 2050, 2020, 1604 cm^-1. ¹H NMR: δ = 3.77 (3 H, s), 4.10 (2 H, s), 6.68 (1 H, d, J = 10.1 Hz), 6.71 (1 H, s), 6.79 (1 H, d, J = 8.3 Hz), 6.92 (1 H, d, J = 10.1 Hz), 7.16 (1 H, d, J = 8.3 Hz). ¹³C NMR: δ = 199.3 (br), 158.3, 138.6, 132.8, 130.5, 130.0, 129.3, 117.7, 113.9, 102.9, 86.6, 55.3, 39.9. MS (EI): m/z = 456 [M]⁺, 428 [M - CO]⁺, 400 [M - 2 CO]⁺, 372 [M - 3 CO]⁺, 344 [M - 4 CO]⁺, 316 [M - 5 CO]⁺, 288 [M - 6 CO]⁺. HRMS (EI): m/z calcd for C₁₈H₁₀Co₂O₇: 455.9090; found: 455.9051.
Compound 2e: IR (neat, KBr): ν_max = 3026, 2935, 2090, 2052, 2022, 1602, 1556 cm^-1. ¹H NMR: δ = 3.88 (3 H, s), 5.35 (1 H, s), 6.77 (1 H, dd, J = 8.6, 2.6 Hz), 6.82 (1 H, s), 6.83 (1 H, m), 7.01 (1 H, d, J = 10.1 Hz), 7.09 (1 H, d, J = 8.5 Hz), 7.23 (1 H, m), 7.29 (2 H, m), 7.35 (2 H, m). ¹³C NMR: δ = 199.4 (br), 158.3, 144.4, 138.3, 133.5, 133.1, 131.3, 129.6, 128.6, 127.0, 118.4, 114.2, 107.1, 84.8, 55.4, 55.3. MS (EI): m/z = 504 [M - CO]⁺, 476 [M - 2 CO]⁺, 448 [M - 3 CO]⁺, 420 [ M - 4 CO]⁺, 392 [M - 5 CO]⁺, 364 [M - 6 CO]⁺. HRMS (EI): m/z calcd for C₂₄H₁₄Co₂O₇: 503.9454 [M - CO]⁺; found: 503.9437.
Compound 2f: IR (neat, KBr): ν_max = 3025, 2928, 2092, 2051, 2020. ¹H NMR: δ = 4.47 (2 H, s), 6.31 (1 H, s), 6.39 (1 H, d, J = 9.6 Hz), 6.57 (1 H, d, J = 9.6 Hz), 7.30 (1 H, s). ¹³C NMR: δ = 199.3 (br), 148.8, 140.8, 125.1, 124.1, 120.5, 113.3, 92.2, 86.6, 34.0. MS (EI): m/z = 416 [M]⁺, 388 [M - CO]⁺, 360 [M - 2 CO]⁺, 332 [M - 3 CO]⁺, 304 [M - 4 CO]⁺, 276 [M - 5 CO]⁺, 248 [M - 6 CO] ⁺ . HRMS (EI): m/z calcd for C₁₅H₆Co₂O₇: 415.8777 [M]⁺; found: 415.8752.
Compound 2g: IR (neat, KBr): ν_max = 2926, 2856, 2092, 2055, 2024, 1699, 1650, 1540 cm^-1. ¹H NMR: δ = 4.45 (2 H, s), 6.68 (1 H, AB quartet, J = 16.0 Hz), 6.74 (1 H, AB quartet, J = 16.1 Hz), 6.88 (1 H, d, J = 8.7 Hz), 7.08 (1 H, d, J = 8.8 Hz); resonances for minor regioisomer (2g′) could be observed (in CD₃CN) at δ = 4.34 (2 H, s), 6.66 (1 H, d, J = 9.9 Hz), 6.80 (1 H, d, J = 9.7 Hz), 7.20 (1 H, s), 7.38 (1 H, s). ¹³C NMR: δ = 199.1 (br), 136.8, 136.7, 132.0, 126.4, 126.2, 122.0, 97.6, 86.8, 34.6; resonances for the minor regioisomer could be observed at δ = 128.7, 126.9, 124.8, 35.5. MS (EI) m/z = 432 [M]⁺, 404 [M - CO]⁺, 376 [M - 2 CO]⁺, 348 [M - 3 CO]⁺, 320 [M - 4 CO]⁺, 292 [M - 5 CO]⁺, 264 [M - 6 CO]⁺. HRMS (EI): m/z calcd for C₁₅H₆Co₂O₆S: 403.8575 [M - CO]⁺; found: 403.8554.
Compound 2j: IR (neat, KBr): ν_max = 3055, 2090, 2051, 2021, 1594 cm^-1. ¹H NMR: δ = 3.78 (3 H, s), 3.83 (3 H, s), 3.91 (3 H, s), 4.05 (2 H, s), 6.62 (1 H, s), 6.93 (1 H, d, J = 10.4 Hz), 7.12 (1 H, d, J = 10.4 Hz). ¹³C NMR: δ = 199.4, 153.3, 152.8, 141.4, 134.3, 127.7, 125.9, 124.7, 108.4, 102.9, 87.7, 61.1, 61.0, 56.0, 41.1. MS (EI): m/z = 516 [M]⁺, 460 [M - 2 CO]⁺, 404 [M - 4 CO]⁺. HRMS: m/z calcd for C₂₀H₁₄Co₂O₉: 403.9505 [M - 4 CO]⁺; found: 403.9492.
Compound 2k: IR (neat, KBr): ν_max = 3014, 2957, 2360, 2091, 2052, 2022 cm^-1. ¹H NMR: δ = 0.28 (9 H, s), 4.20 (2 H, s), 6.76 (1 H, d, J = 10.1 Hz), 6.94 (1 H, d, J = 10.1 Hz), 7.16 (1 H, d, J = 7.5 Hz) 7.36 (1 H, s), 7.37 (1 H, d, J = 6.2 Hz). ¹³C NMR: δ = 199.4 (br), 142.0, 137.7, 136.3, 134.2, 133.2, 131.9, 131.7, 129.0, 102.4, 86.6, 40.9, -1.2. MS (EI) m/z = 498 [M]⁺, 470 [M - CO]⁺, 442 [M - 2 CO]⁺, 414 [M - 3 CO]⁺, 386 [M - 4 CO]⁺, 358 [M - 5 CO]⁺, 330 [M - 6 CO]⁺. HRMS (EI): m/z calcd for C₂₀H₁₆Co₂O₆Si: 469.9431 [M - CO]⁺; found: 469.9434.

18 Hosokawa S. Isobe M. Tetrahedron Lett.  1998,  39:  2609