Ruthenium Indenylidene and Vinylidene Complexes bearing Schiff Bases: Potential Catalysts in Enol-Ester Synthesis

Tom Opstal; Francis Verpoort

doi:10.1055/s-2002-31892

LETTER

Ruthenium Indenylidene and Vinylidene Complexes bearing Schiff Bases: Potential Catalysts in Enol-Ester Synthesis

Tom Opstal, Francis Verpoort*
Department of Inorganic and Physical Chemistry, Organometallics and Catalysis Division, Ghent University, Krijgslaan 281 (S3), 9000 Ghent, Belgium
Fax: +32(9)2644983; e-Mail: Francis.Verpoort@rug.ac.be;

Abstract

All articles of this category

Abstract

In an extension of our previous investigations on the ruthenium(II) Schiff-base chemistry, complexes 1, 2, 3a-b and 4a-b were synthesized and tested as catalyst for the nucleophilic addition of carboxylic acids to terminal alkynes. A careful choice of the catalytic system, substrate and carboxylic acid can provide alk-1-en-2-yl esters, alk-1-en-1-yl esters synthesis or enyne dimerization. In this way substituted isopropenol and α-methylenebenzyl formates, (geminal, geminal) dienol diesters were synthesized in one step by direct addition of formic acid or benzoic acid to terminal mono- and di-ynes.

Key words

ruthenium - Schiff base - vinylidene - indenylidene - enol ester synthesis - homogeneous catalysis

Full Text

References

1 Bruce MI. Chem. Rev. 1991, 22: 59

2a Trost BM. Chem. Ber. 1996, 129: 1313

2b Bruneau C. Dixneuf PH. Acc. Chem. Res. 1999, 32: 311

3a Katayama H. Yoshida T. Ozawa F. Chem. Lett. 1998, 67

3b Yi CS. Liu N. Synlett 1999, 281

3c Na Y. Chang S. Org. Lett. 2000, 1887

3d Das SK. Roy R. Tetrahedron Lett. 1999, 40: 4015

4a Cadierno V. Gamassa MP. Gimeno J. González-Cueva M. Lastra E. Borge J. García-Granda S. Pérez-Carreño E. Organometallics 1996, 15: 2137

4b Kückückbay H. Cetinkaya B. Guesmi S. Dixneuf PH. Organometallics 1996, 15: 2434

5 Bruneau C. Dixneuf PH. J. Chem. Soc., Chem. Commun. 1997, 507

6a Larock RC. Beatty KM. J. Am. Chem. Soc. 1980, 102: 1966

6b Mondal MAS. van der Meer R. German AL. Heikens D. Tetrahedron 1974, 4205

7a Rotem M. Shvo Y. Organometallics 1983, 2: 1689

7b Bruneau C. Neveux M. Kabouche Z. Ruppin C. Dixneuf PH. Synlett 1991, 755

7c Mitsudo T. Hori Y. Yamazaki Y. Watanabe Y. J. Org. Chem. 1987, 52: 2230

8 Doucet H. Martin-Vaca B. Bruneau C. Dixneuf PH. J. Org. Chem. 1995, 60: 7247

9 Gemel C. Trimmel G. Slugovc C. Kremel S. Mereiter K. Scmid R. Kirchner K. Organometallics 1996, 15: 3998

10 Fürstner A. Guth O. Düffels A. Seidel G. Liebl M. Gabor B. Mynott R. Chem.-Eur. J. 2001, 22: 4811

11a Fürstner A. Hill AF. Liebl M. Wilton-Ely JDET. Chem. Commun. 1999, 601

11b Fürstner A. Grabowski J. Lehmann CW. J. Org. Chem. 1999, 64: 8275

12 Katayama H. Ozawa F. Organometallics 1998, 17: 5190

13 For the use of this type of complexes in ATRP and Kharasch addition reactions see: De Clercq B. Verpoort F. Tetrahedron Lett. 2001, 42: 8959

14a Jafarpour L. Schanz J. Stevens ED. Nolan SP. Organometallics 1999, 18: 5416

14b Harlow KJ. Hill AF. Wilton-Ely JDET. J. Chem. Soc., Dalton Trans. 1999, 285

15

Catalyst 2 (Figure [2] ): dark red solid
(79%) ¹H NMR (299.89 MHz, C₆D_6, 25 °C) δ 8.44 (dd, J = 7 Hz, 1H, H-23), 8.17 (s, 1H, H-7), 7.71 (d, J = 4 Hz, 2H, H-26), 7.46 (d, J = 5 Hz, 1H, H-28), 7.44 (dd, J = 8.7, 2.4 Hz, 1H, H-5), 7.38 (dd, J = 6.5, 2.1 Hz, 2H, H-27), 7.37 (s, 1H, H-16), 7.30 (m, 1H, H-21), 7.25 (m, 1H, H-22), 7.23 (dd, J = 7.0, 2.2 Hz, H-20), 6.97 (s, 2H, H-11, H-11), 6.88 (t, J = 6.5 Hz, 1H, H-4), 6.68 (d, J = 9.3 Hz, 1H, H-2), 2.46 (s, 6H, H-10, H-15), 1.85-1.33 (m, 20H, CH₂ of PCy₃), 1.28 (d, J = 6.7 Hz, 3H), 1.15 (m, 10H). ¹³C NMR (75.41 MHz, C₆D₆, 25 °C) 290.6 (s, J _PC = 7.8 Hz, C-16), 162.2 (s, C-7),158.7 (s, C-1), 150.3 (s, C-8), 142.5 (s, C-24), 140.0 (s, C-19), 139.2 (s, C-18), 138.7 (d, J _CH = 175 Hz, C-17), 136.4 (s, C-25), 133. 0 (s, C-9), 131.2 (d, C-3), 130.2 (s, C-11), 129.7 (d, C-5), 129.3 (d, J _CH = 160 Hz, C-23), 129.1 (d, C-22), 128.4 (d, C-21), 128,0 (d, C-28), 126.2 (d, C-26, C-30), 120.9 (d, C-4), 118.2 (s, C-6), 118.0 (d, J _CH = 155 Hz, C-20), 33.7 (CH), 30.2, 30.1, 28.6, 28.3, 21.9 (CH₂ of PCy₃), 16.80 (q, J _CH = 124.9 Hz, C-10, C-16). ³¹P NMR (121,40 MHz, C₆D₆, 25 °C, ref. to H₃PO₄) δ = 39.60 (s). Anal. Calcd for C₄₈H₅₆BrClNOPRu; C, 63.33, H, 6.20, N, 1.54. Found: C, 63.97, H, 6.31, N, 1.70.
Catalyst 3a: brown solid (81%): ¹H NMR (299.89 MHz, C₆D₆, 25 °C): δ 8.20 (d, J = 5.2 Hz, 1H), 7.38 (d, J = 7.0 Hz, 1H), 7.30 (t, J = 7.2 Hz, 1H), 7.22-7.14, 6.99-6.94, 6.89-6.79 (each m, 5H, Ph), 7.13 (s, 2H), 7.06 (t, J = 7 Hz, 1H), 4.36 (t, J = 4.2 Hz, Ru=C=CHPh), 2.14 (s, 3H), 1.61-1.31 (m, 20H), 1.27 (d, J = 6 Hz, 3H), 1.19 (m, 10H); ¹³C NMR (75.41 Hz, C₆D₆, 25 °C): δ 343.6 (d, J _PC = 11.5 Hz, Ru=C=CHPh), 161.25, 154.32, 138.36, 128.49, 118.21, 108.45 (t, J _PC = 5 Hz, Ru=C=CHPh), 31.5 (vt, J = 8.5 Hz, C¹ of C₆H₁₁), 26.16 (s, C^3,5 of C₆H₁₁), 16.76; ³¹P{¹H} NMR (C₆D₆, 25 °C): δ 51.8 Hz (s). Anal. Calcd for C₄₁H₅₂BrClNOPRu; C, 59.89, H, 6.37, N, 1.70. Found: C, 59.93, H, 6.42, N, 1.79.
Catalyst 3b: dark brown solid (80%): ¹H NMR (299.89 MHz, C₆D₆, 25 °C): δ 8.24 (d, J = 2.5 Hz, 1H), 8.08 (dd, J = 9 Hz, 2.4 Hz, 1H), 7.94 (d, J = 5.6 Hz, 1H), 7.56 (t, J = 7.5 Hz, 1H), 7.29 (d, J = 9.8 Hz, 1H), 7.16 (s, 2H), 7.13-7.07 (o-H), 7.02-6.96 (p-H), 6.89-6.80 (m-H) (each m, 5H, Ph), 4.25 (t, J = 5 Hz, Ru=C=CHPh), 2.44 (q, J = 11 Hz, 3H), 2.34 (s, 3H), 1.70-1.63 (br s, 20H, C₆H₁₁), 1.54 (d, J = 12 Hz, 3H), 1.36-1.08 (br s, 20H); ¹³C NMR (75.41 Hz, C₆D₆, 25 °C): δ 340.3 (d, J _PC = 10 Hz, Ru=C=CHPh), 165.3, 162.8, 141.9, 137.7, 132.9 (s, C¹ of Ph), 128.2, 125.5, 121.6 (each s, C^2,6 of C₆H₁₁), 117.7, 111.8, 108.3 (t, J _PC = 5 Hz, Ru = C = C); ³¹P{¹H} NMR (C₆D₆, 25 °C): δ 49.07 Hz (s). Anal. Calcd for C₄₁H₅₁BrClN₂O₃PRu; C, 56.78, H, 5.93, N, 3.23. Found: C, 56.81, H, 6.32, N, 3.30.
Catalyst 4a: dark brown solid(78%): ¹H NMR (299.89 MHz, C₆D₆, 25 °C): δ 8.28 (d, J = 2.7Hz, 1H), 7.42 (d, J = 7.2 Hz, 1H), 7.23 (t, J = 7.0 Hz, 1H),7.06 (m, 3H), 6.74 (d, J = 6.7 Hz, 1H), 2.83 (t, J = 3 Hz, Ru=C=CH t-Bu), 1.78-1.50 (m, 23H), 1.26-1.15 (m, 10H), 1.08 (s, 9H, t-Bu); ¹³C NMR (75.41 Hz, C₆D₆, 25 °C): δ 330.9 (t, J _PC = 13.6 Hz, Ru=C=CHBut^t), 162.2, 158.4, 130.3, 106.0 (t, J_PC = 5.3 Hz, Ru = C = CHBut^t), 35. 1 (vt, J = 9 Hz, C¹ of C₆H₁₁), 26.6
[s, C(CH₃)₃], 21.2 (s, C^3,5 of C₆H₁₁), 19.9 [s, C(CH₃)₃], 16.5; ³¹P{¹H} NMR (C₆D_6, 25 °C): δ 47.443 (s). Anal. Calc for C₃₉H₅₆BrClNOPRu; C, 58.39, H, 7.04, N, 1.75. Found: C, 58.43, H, 7.20, N, 1.89.
Catalyst 4b: brown solid (70%): ¹H NMR (299.89 MHz, C₆D₆, 25 °C): δ 8.30 (d, J = 2.9 Hz, 1H), 7.6 (dd, J = 9, 2.3 Hz, 1H), 7.37 (d, J = 5 Hz, 1H), 7.13 (s, 2H), 6.99 (d, J = 9.8 Hz 1H), 3.06 (t, J = 4 Hz, Ru=C=CH t-Bu), 2.50 (q, J = 12 Hz, 3H), 2.38 (s, 3H), 1.88-1.75 (br s, 20H), 1.60 (d, J = 12.5 Hz, 3H), 1.34-25 (m, 10H), 1.07 (s, 9H, t-Bu); ¹³C NMR (75.41 Hz, C₆D₆, 25 °C): δ 333.20 (t, J _PC = 13.4 Hz, Ru=C=CHt-Bu), 162.02, 157.32, 138.39, 127. 91, 118.16, 111.7 (t, J _PC = 5 Hz, Ru=C=CHt-Bu), 36.20 (vt, J = 8.8 Hz, C¹ of C₆H₁₁), 31.30 (s, C(CH₃)₃, 28.25 (s, C^3,5 of C₆H₁₁), 23.82 [s, C(CH₃)₃], 17.48; ³¹P{¹H} NMR (C₆D_6, 25 °C): δ 45.1 (s). Anal. Calcd for C₃₉H₅₅BrClN₂O₃Pru; C, 55.29, H, 6.54, N, 3.31. Found: C, 55.54, H, 7.13, N, 3.60.

16a Slugovc C. Mereiter K. Zobetz E. Schmid R. Kirchner K. Organometallics 1999, 15: 5275

16b Amos RA. Katzenellenbogen JA. J. Org. Chem. 1978, 43: 560

16c Mitsudo T. Hori Y. Yamakawa Y. Watanabe Y. J. Org. Chem. 1987, 52: 2230

17 Kabouche A. Kabouche Z. Bruneau C. Dixneuf PH. J. Chem. Res. (S) 1999, 249

18

De Clercq, B.; Verpoort, F. Adv. Synth. Cat. 2002, accepted for publication.

19a Philippot K. Devanne D. Dixneuf PH. J. Chem. Soc., Chem. Commun. 1990, 1199

19b Kita Y. Maeda H. Omori K. Okuno T. Tamura Y. Synlett 1993, 273