A theoretical study of Favorskii reaction stereochemistry. Lessons in torquoselectivity

Journal of Organic Chemistry

Volumn 72, Issue 21, 2007, Pages 8033-8045

  Hamblin, Graham D ^a   Jimenez, Raphael P ^a   Sorensen, Ted S ^a  

^a UNIVERSITY OF CALGARY   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

CHLOROENOLATE; FAVORSKII REACTION; TORQUOSELECTIVITY; TRANSITION STATE;

ACETONE; DERIVATIVES; ENANTIOMERS; HEXANE; REACTION KINETICS; SOLVATION;

STEREOCHEMISTRY;

1 ACETYL 1 CHLOROCYCLOHEXANE; ACETONE; ALLYL COMPOUND; CHLORINE DERIVATIVE; CYCLOHEXANE DERIVATIVE; METHYL GROUP; SOLVENT; UNCLASSIFIED DRUG;

AB INITIO CALCULATION; ARTICLE; CHEMICAL REACTION; CHEMICAL STRUCTURE; ENANTIOMER; ENERGY; FAVORSKII REARRANGEMENT; GEOMETRY; REACTION ANALYSIS; SIMULATION; SOLVATION; STEREOCHEMISTRY; STRUCTURE ANALYSIS; THEORETICAL MODEL; THEORETICAL STUDY;

EID: 35348845751     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo701351p     Document Type: Article

References (63)

1. Reviews: (a) Kende, A. S. Org. React. 1960, 11, 261-316.
2. (b) Chenier, P. J. Chem. Educ. 1978, 55, 286.
3. (c) Hunter, D. H.; Stothers, J. B.; Warnhoff, E. W. In Rearrangements in Ground and Excited States; de Mayo, P., Ed.; Academic Press: New York, 1980; Vol. 1, p 391.
4. (d) Baretto, A.; Waegill, B. Reactive Intermediates; Abramovitch, R. A., Ed.; Plenum Press: New York, 1982; pp 527-585.
5. (e) Mann, J. Compr. Org. Synth. 1991, 3, 839-859.
6. (a) Aston, J. G.; Newkirk, J. D. J. Am. Chem. Soc. 1951, 73, 3900.
7. (b) Sacks, A. A.; Aston, J. G. J. Am. Chem. Soc. 1951, 73, 3902.
8. 4 and (b) an unsymmetrical cyclopropanone intermediate can in principle open to give two different esters (see Scheme 2, intermediate B). In Scheme 2, the observed product could only have formed via the "normal" mechanism.
9. Warnhoff, E. W.; Wong, C. M.; Tai, W. T. J. Am. Chem. Soc. 1968, 90, 514-515.
10. N2" have been used to describe the inversion mechanism, and this step is often shown in textbooks and research papers using a displacement arrow formalism.
11. Bordwell has described the proposal for an oxyallyl " intermediate" as the Aston-Dewar mechanism. (a) Bordwell, F. G.; Frame, R. R.; Scamehorn, R. G.; Strong, J. G.; Meyerson, S. J. Am. Chem. Soc. 1967, 89, 6704-6709.
12. (b) Bordwell, F. G.; Scamehorn, R. G. J. Am. Chem. Soc. 1968, 90, 6751-6758.
13. Stork, G.; Borowitz, I. J. J. Am. Chem. Soc. 1960, 82, 4307.
14. House, H. O.; Gilmore, W. F. J. Am. Chem. Soc. 1961, 83, 3980.
15. See also: Skrobek, A.; Tchoubar, B. C. R. Acad. Sci. (Paris) 1966, 263, 80-83.
16. N1 (retention) terminology. Miller, B. Advanced Organic Chemistry. Reactions and Mechanisms; Prentice Hall, Inc.: Upper Saddle River, NJ, 1998; Chapter 8.1, p 221.
17. (a) Loftfield, R. B. J. Am. Chem. Soc. 1950, 72, 632.
18. (b) Loftfield, R. B. J. Am. Chem. Soc. 1951, 73, 4707.
19. Substituted bicyclo[3.1.0]hexan-6-ones have been prepared and characterized in situ using Favorskii-like experimental conditions: Sorensen, T. S.; Sun, F., Can. J. Chem. 1996, 74, 79-87.
20. (a) Lee, E.; Yoon, C. C. J. Chem. Soc., Chem. Commun. 1994, 479-481.
21. (b) Lee, E.; Yoon, C. H.; Lee, Y. J.; Kim, H. J. Bull. Korean Chem. Soc. 1997, 18, 1247-1248.
22. (c) Lee, E.; Lim, J. W.; Yoon, C. H.; Sung, Y.; Kim, Y. K. J. Am. Chem. Soc. 1997, 119, 8391-92.
23. See also: Oliver, S. F.; Högenauer, K.; Simic, O.; Antonello, A.; Smith, M. S.; Ley, S. V. Angew. Chem., Int. Ed. 2003, 42, 5996-6000.
24. The cyclopropanone ring opening as in (B) has been shown to occur with retention of configuration: Wharton, P. S.; Fritzberg, A. R. J. Org. Chem. 1972, 37, 1899-1902.
25. 15
26. However for an example of this, see the preparation of trans-2,3-di-tert-butylcyclopropanone under Favorskii-like conditions: Pazos, J. F.; Pacifici, J. G.; Pierson, G. G.; Sclove, D. B.; Greene, F. D. J. Org. Chem. 1974, 39, 1990-95.
27. This product is almost certainly produced by the base-catalyzed isomerization of the first formed cis-2,3-di-tert-butylcyclopropanone, see: Sorensen, T. S.; Sun, F. Can. J. Chem. 1997, 75, 1030-1040.
28. (a) Castillo, R.; Andrés, J.; Moliner, V. J. Phys. Chem. B 2001, 105, 2453-2460.
29. (b) Moliner, V.; Castillo, R.; Safont, V. S.; Oliva, M.; Bohn, S.; Tuñón, I.; Andrés, J. J. Am. Chem. Soc. 1997, 119, 1941-1947.
30. Schaad, L. J.; Andes Hess, B., Jr.; Zahradník, R. J. Org. Chem. 1981, 46, 1909-1911.
31. Gaussian 03, Revision A.1, Frisch, M. J. et al. Guassian, Inc, Pittsburgh PA, 2003. A full list of authors is given in the Supporting Information.
32. (a) Grimme, S. J. Chem. Phys. 2003, 118, 9095-9102.
33. (b) Goumans, T. P.; Ehlers, A. W.; Lammertsma, K.; Wurthwein, E. U.; Grimme, S. Eur. J. Chem. 2004, 10, 6468-6475.
34. Tomasi, J.; Persico, M. Chem. Rev. 1994, 94, 2027.
35. 6 have carried out extensive Favorskii rearrangement studies using deuterated (-OD) solvents. The extent of H-D exchange at the enolate position (the α′-position in their nomenclature) is usually not complete and is quite variable in different systems. These authors have also used Hammett σ-ρ studies to show that there is extensive C-Cl bond weakening in the transition state for the cyclopropanone-forming step.
36. We have not attempted a full statistical treatment in those cases where the two GSs are close in energy. This would involve including the calculated entropies and thermal parameters in the ΔG calculations.
37. (a) Coolidge, M.; Yamashita, K.; Morokuma, K.; Borden, W. T. J. Am. Chem. Soc. 1990, 112, 1751-54.
38. (b) Ichimura, A. S.; Lahti, P. M.; Matlin, A. R. J. Am. Chem. Soc. 1990, 112, 2868-75.
39. (c) Lim, D.; Hrovat, D. A.; Borden, W. T.; Jorgensen, W. L. J. Am. Chem. Soc. 1994, 116, 3494.
40. (d) Hess, Jr., B. A.; Eckhart, U.; Fabian, J. J. Am. Chem. Soc. 1998, 120, 12310-12315.
41. 23d (UB3LYP) found a somewhat further advanced TS, C-C-C angle = 104.8°. For our inversion TS, this angle is 90.6°, and 102° for retention (B3LYP and MP2).
42. Multireference CASSCF calculations are often carried out on systems with triplet instabilities, but these calculations (with added dynamic correlation methods) require large computer resources and there is some arbitrariness regarding the size of the active space to be used.
43. Chloroenolate 6 also has enantiomeric TSs for both inversion and retention reactions, but these are trivial since an identical "product" results.
44. Stereochemistry of Organic Compounds; Eliel, E. L., Wilen, S. H., Eds.; John Wiley and Sons, Inc.: New York, 1994; pp 726-730.
45. Cossi, M.; Rega, N.; Scalmani, G.; Barone, V. J. Comput. Chem. 2003, 24, 669-681.
46. For a discussion of solvation modeling, see Cramer, C. J.; Truhlar, D. G. Science 1992, 256, 213.
47. The chloride anion "solvation" energy provides the largest driving force.
48. On a free energy basis, the positive entropy change in going to the products will further contribute to the exergonicity of the reaction.
49. Organic Chemistry; Clayden, J., Greeves, N., Warren, S., Wothers, P., Eds.; Oxford University Press: New York, 2001; pp 990-991.
50. On examination of the structure of the inversion GS for 6, one already finds a slight nonplanarity in the enolate (±1.277°) in the selective rotation direction eventually leading to the TS.
51. 23d and in the GS structure of bicyclo[1.1.0]butan-2-ones: Barghava, S.; Hou, J.; Parvez, M.; Sorensen, T. S. J. Am. Chem. Soc. 2005, 127, 3704-3705. All of the other TSs obtained in our study showed the same distortion.
52. At a C-Cl distance of 2.1 Å, the enolate dihedral angle is 3.6°, 9.7° at C-Cl = 2.3 Å, and 17.8° at 2.5 Å. For the parent system 6, the corresponding values are 5.5°, 7°, and 12°. The use of IRC energy profiles in cases where one is attempting to distinguish between a bond dissociation mechanism involving a flat profile concerted reaction vs a short-lived intermediate (shallow PE minimum) has been questioned: Ussing, B. R.; Singleton, D. A. J. Am. Chem. Soc. 2005, 127, 2888-2899.
53. 23c of the oxyallyl system indicate an extremely low barrier for cyclization (0.33 kcal/mol); i.e., oxyallyl is almost a transition state in itself.
54. Solvation simulations use the Born equation, where solvation energies vary as 1 - 1/ε = dielectric constant). The relative solvation energies for gas phase, DME, and methanol become 0:0.8:0.97. For a solvation energy of 60 kcal/mol in methanol, one has a value of about 50 kcal/mol in DME. For a calculated difference of 2 kcal/mol solvation energy between two solutes in methanol, one has a difference in DME of 1.7 kcal/mol, i.e., a 0.3 kcal/mol difference.
55. Burr, Jr., J. G.; Dewar, M. J. S. J. Chem. Soc. 1954, 1201-1203.
56. The α-chlorocyclohexanone retention mechanism leading to bicyclo-[3.1.0]hexan-6-one appears to be the least concerted of the retention mechanisms studied in this work, cf. a comparison of the IRC profile in Figure 8 for chloroenolate 7, vs that in Figure 10 for the α- chlorocyclohexanone enolate 12. This difference is probably a result of the ring restricted O-C-C-Cl dihedral angle in the retention GS of 12 (72°), compared to the >90° in most of the enolates where "free" rotation is possible.
57. (a) Bordwell, F. G.; Scamehorn, R. G.; Springer, W. R. J. Am. Chem. Soc. 1969, 91, 2087-2093.
58. (b) Bordwell, F. G.; Carlson, M. W. J. Am. Chem. Soc. 1970, 92, 3370-3377.
59. (c) Bordwell, F. G.; Almy, J. J. Org. Chem. 1973, 38, 575-578.
60. Engel, Ch. R.; Mérand, Y.; Côté, J. J. Org. Chem. 1982, 47, 4485-4491.
61. See footnotes 31 and 33 of ref 40.
62. Sorensen, T. S.; Sun, F. J. Chem. Soc., Perkin Trans. 2 1998, 1053-1061.
63. Föhlisch, B.; Gerlach, E.; Stezowski, J. J.; Kollat, P.; Martin, E.; Gottstein, W. Chem. Ber. 1986, 119, 1661.