Coordination of iron(III) cations to β-keto esters as studied by electrospray mass spectrometry: Implications for iron-catalyzed michael addition reactions

Chemistry - A European Journal

Volumn 11, Issue 2, 2005, Pages 619-627

  Trage, Claudia ^a   Schröder, Detlef ^a   Schwarz, Helmut ^a  

^a TECHNISCHE UNIVERSITÄT BERLIN   (Germany)

Author keywords

Electrospray ionization; Enolates; Iron; Keto esters; Mass spectrometry; Michael addition

Indexed keywords

ADDITION REACTIONS; ALKALINITY; CATALYSIS; COMPLEXATION; ESTERS; IONIZATION; MASS SPECTROMETRY; REACTION KINETICS; SALTS;

BINDING AFFINITIES; CATALYTIC CYCLES; ELECTROSPRAY IONIZATION; MICHAEL ADDITIONS;

IRON;

COORDINATION COMPOUND; ESTER DERIVATIVE; IRON COMPLEX; KETONE DERIVATIVE;

ALKALINITY; ARTICLE; CATALYSIS; CHEMICAL STRUCTURE; CONCENTRATION (PARAMETERS); ELECTROSPRAY MASS SPECTROMETRY; MICHAEL ADDITION;

EID: 12444281014     PISSN: 09476539     EISSN: None     Source Type: Journal    
DOI: 10.1002/chem.200400715     Document Type: Article

References (45)

1. J. Christoffers, Synlett 2001, 723-732.
2. J. Christoffers, Chem. Commun. 1997, 943-944.
3. J. Christoffers, J. Chem. Soc. Perkin Trans. 1 1997, 3141-3150.
4. J. Christoffers, H. Oertling, N. Önal, J. Prakt. Chem. 2000, 342, 546-553.
5. J. Christoffers, Tetrahedron Lett. 1998, 39, 7083-7084.
6. J. Christoffers, H. Oertling, Tetrahedron 2000, 56, 1339-1344.
7. J. Christoffers, H. Oertling, M. Leitner, Synlett 2000, 349-350.
8. S. Pelzer, T. Kauf, C. van Wüllen, J. Christoffers, J. Organomet. Chem. 2003, 684, 308-314.
9. 2) into a high voltage electric field. The droplets formed contain the solvent and also the ions that have been present in solution. Some droplets will carry a small excess charge. These droplets will be affected by the applied electric field. Due to the drying gas these droplets shrink as solvent molecules evaporate. After falling short of a critical diameter (strictly speaking, the charge-to-surface ratio), the droplets explode due to increasing Coulomb forces of the remaining ions. Due to these two processes (evaporation of solvent and Coulomb explosion), the average diameter of the droplets becomes smaller and smaller until only single ionic molecules (partly solvated) remain in the gas phase and are transferred into the analyzing region of the mass spectrometer.
10. D. A. Plattner, Int. J. Mass Spectrom. 2001, 207, 125-144.
11. 2 and in neat ester solutions, but cannot be detected if alcoholic solvents are employed.
12. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, Butterworth Heinemann, Oxford (UK), 1998, pp. 1070-1112.
13. E. V. Dose, K. M. M. Murphy, L. J. Wilson. Inorg. Chem. 1976, 15, 2622-2630.
14. R. L. Lintvedt, L. K. Kernitsky, Inorg. Chem. 1970, 9, 491-494.
15. [19] and the formation of a 19-electron complex is assumed to be unfavorable in this case.
16. N. V. Novozhilova, T. N. Polynova, M. A. Porai-Koshils, N. I. Pechurova, L. I. Martynenko, A. Khadi, Zh. Strukt. Khim. 1973, 14, 745-746.
17. N. V. Novozhilova, T. N. Polynova, M. A. Porai-Koshits, L. I. Martynenko, Zh. Strukt. Khim. 1974, 15, 717.
18. X. Solans, M. Font-Altaba, J. Garcia-Oricain, Afinidad 1984, 41, 572-574.
19. J. S. Moore, A Coordination Geometry Table of the d-Block Transition Elements and their Ions, http://sulfur.scs.uiuc.edu/.
20. 3. From the absence of methyl-transfer processes in the iron-free solution, it can be deduced that the etherification is an iron-mediated reaction.
21. Likewise, a corresponding ethyl transfer is observed for the elhyl esters concomitant with a mass shift of Δm = +28.
22. R. B. Cole, Electrospray Ionization Mass Spectrometry: Fundamentals, Instrumentation and Applications, Wiley, New York, 1997
23. S. Pelzer, Ph.D. Thesis, Technische Universität Berlin, D83, 2004.
24. N. B. Cech, C. G. Enke, Mass Spectrom. Rev. 2001, 20, 362-387.
25. +.
26. R. G. Cooks, P. S. H. Wong, Acc. Chem. Res. 1998, 31, 379-386.
27. R. G. Pearson, R. L. Dillon, J. Am. Chem. Soc. 1953, 75, 2439-2443.
28. R. Brouillard, J.-E. Dubois, J. Org. Chem. 1974, 39, 1137-1142.
29. B. V. Kurgane, M. T. Brakmane, Y. P. Stradyn, S. A. Giller, J. Org. Chem. USSR 1975, 917-921.
30. J. W. Bunting, J. P. Kanter, J. Am. Chem. Soc. 1993, 115, 11705-11715.
31. H. F. Ebel, "Metallorganische Verbindungen", in Methoden Org. Chem. (Houben-Weyl) 4th ed. 1952-, Vol. XIII/1, 1970, p. 76.
32. S. J. Rhoads, A. W. Decora, Tetrahedron 1963, 19, 1645-1659.
33. [41] and 3) it has to be taken into account that the proton affinities mentioned here refer to the gas phase where no solvation effects are operative. These three effects cause a further stabilization of the coordinated proton and hence increase its proton affinity. Therefore, the influence of the alkoxy moiety alone on the proton affinity for the esters 1a, 1b, and 1e is expected to be less pronounced than for the respective alkyl acetates. Consequently, proton affinities of the esters 1a, 1b, and 1e can only be estimated and the difference in PAs is not expected to be large. Moreover, the expected trend will be opposed to the steric effect and both trends might therefore by and large cancel each other.
34. J. S. Uppal, R. H. Staley, J. Am. Chem. Soc. 1982, 104, 1235-1238.
35. J. S. Uppal, R. H. Staley, J. Am. Chem. Soc. 1982, 104, 1238-1243.
36. M. M. Kappes, R. H. Staley, J Am. Chem. Soc. 1982, 104, 1813-1819.
37. M. M. Kappes, R. H. Staley, J. Am. Chem. Soc. 1982, 104, 1819-1823.
38. R. W. Jones, R. H. Staley, J. Am. Chem. Soc. 1982, 104, 2296-2300.
39. R. W. Jones, R. H. Staley, J. Phys. Chem. 1982, 86, 1387-1392.
40. D. Schröder, H. Schwarz, J. Hrušák, P. Pyykkö, Inorg. Chem. 1998, 37, 624-632.
41. E. P. L. Hunter, S. G. Lias, J. Phys. Chem. Ref. Data 1998, 27, 413-457.
42. D. Schröder, T. Weiske, H. Schwarz, Int. J. Mass Spectrom. 2002, 219, 729-738.
43. The ethyl esters 1b-d were measured in ethanol, while the methyl ester la was measured in methanol to avoid transesterification.
44. M. Kohler, J. A. Leary, Int. J. Mass Spectrom. Ion Processes 1997, 162, 17-34.
45. Calculated using the Sheffield Chemputer, see: http://www.shef. ac.uk/chemistry/chemputer (©Mark Winter, University of Sheffield, UK, 1993-2001).