On the relative preference of enamine/iminium pathways in an organocatalytic michael addition reaction

Chemistry - An Asian Journal

Volumn 4, Issue 5, 2009, Pages 714-724

  Patil, Mahendra P ^a   Sunoj, Raghavan B ^a  

^a INDIAN INSTITUTE OF TECHNOLOGY BOMBAY   (India)

Author keywords

Ab initio calculations; Density functional calculations; Explicit solvents; Michael addition; Organocatalysis

Indexed keywords

AB INITIO CALCULATIONS; DENSITY FUNCTIONAL CALCULATIONS; EXPLICIT SOLVENTS; MICHAEL ADDITION; ORGANOCATALYSIS;

ACTIVATION ENERGY; AMINES; CATALYSIS; CATALYSTS; DENSITY FUNCTIONAL THEORY; KETONES; RATE CONSTANTS; REACTION KINETICS; SOLVENTS;

ADDITION REACTIONS;

EID: 67650498328     PISSN: 18614728     EISSN: 1861471X     Source Type: Journal    
DOI: 10.1002/asia.200800351     Document Type: Article

References (106)

1. B. E. Rossiter, M. N. Swingle, Chem. Rev. 1992, 92, 771;
2. J. Leonard, E. Diez-Berra, S. Merino, Eur. J. Org. Chem. 1998, 2051;
3. F. Krause, A. Hoffmann-Roder, Synthesis 2001, 171;
4. M. P. Sibi, S. Manyen, Tetrahedron 2000, 56, 8033;
5. O. E. Berner, L. Tedeschi, D. Enders, Eur. J. Org. Chem. 2002, 1877.
6. P. I. Dalko, I. Moison, Angew. Chem. 2001, 113, 3840;
7. Angew. Chem. Int. Ed. 2001, 40, 3726;
8. B. List, Tetrahedron 2002, 58, 5573;
9. J. Seayad, B. List, Org. Biomol. Chem. 2005, 3, 719;
10. P. I. Dalko, I. Moison, Angew. Chem. 2004, 116, 5248;
11. Angew. Chem. Int. Ed. 2004, 43, 5138;
12. B. List, Chem. Commun. 2006, 819;
13. M. J. Gaunt, C. C. C. Johansson, A. McNally, N. T. Vo, Drug Discovery Today 2007, 12, 8;
14. H. Pellissier, Tetrahedron 2007, 63, 9267.
15. S. B. Tsogoeva, Eur. J. Org. Chem. 2007, 1701;
16. S. Mukherjee, J. W. Yang, S. Hoffmann, B. List, Chem. Rev. 2007, 107, 5471 and references therein.
17. P. Melchiorre, K. A. Jørgensen, J. Org. Chem. 2003, 68, 4151.
18. T. J. Peelen, Y. Chi, S. M. Gellman, J. Am. Chem. Soc. 2005, 127, 11598.
19. A. Erkkilä, I. Majander, P. M. Pihko, Chem. Rev. 2007, 107, 5416 and references therein.
20. M. Marigo, T. Schulte, J. Franzen, K. A. Jørgensen, J. Am. Chem. Soc. 2005, 127, 15710;
21. M. Marigo, S. Bertelsen, A. Landa, K. A. Jørgensen, J. Am. Chem. Soc. 2006, 128, 5475;
22. S. Brandau, E. Maerten, K. A. Jørgensen, J. Am. Chem. Soc. 2006, 128, 14986;
23. D. Enders, M. R. M. Huttl, C. Grondal, G. Raabe, Nature 2006, 441, 861;
24. A. Carlone, S. Cabrera, M. Marigo, K. A. Jørgensen, Angew. Chem. 2007, 119, 1119;
25. Angew. Chem. Int. Ed. 2007, 46, 1101.
26. Y. Chi, S. M. Gellman, Org. Lett. 2005, 7, 4253.
27. K. N. Rankin, J.W. Gauld, R. J. Boyd, J. Phys. Chem. A 2002, 106, 5155.
28. G. Evans, T. J. K. Gibbs, R. L. Jenkins, S. J. Coles, M. B. Hursthouse, J. A. Platts, N. C. O. Tomkinson, Angew. Chem. 2008, 120, 2862;
29. Angew. Chem. Int. Ed. 2008, 47, 2820.
30. M. P. Patil, R. B. Sunoj, J. Org. Chem. 2007, 72, 8202.
31. In general, bulky variants of pyrrolidine, such as diphenylprolinol methyl ether, are employed as a catalyst in the Michael addition of aldehydes to enones. We believe that the role of bulky substituents on the catalyst is more important for imparting stereoselectivity to the product rather than the activation of substrate. Since our studies are directed toward establishing the mechanism of reaction, for sake of convenience, the pyrrolidine is taken for modeling transition states instead of substituted pyrrolidiene.
32. While catechol is reported to be a suitable co-catalyst for the Michael addition of aldehydes to enones, other hydrogen bond donor co-catalysts (additives) such as benzoic acid, thiourea, trifluroacetic acid etc., are also found to be of use. These reactions are proposed to involve enamine/iminium ion intermediates. S. Bertelsen, M. Marigo, S. Brandes, P. Dinér, K. A. Jørgensen, J. Am. Chem. Soc. 2006, 128, 12973;
33. W. Wang, H. Li, J. Wang, L. Zu, J. Am. Chem. Soc. 2006, 128, 10354;
34. D. Menche, J. Hassfeld, J. Li, G. Menche, A. Ritter, S. Rudolph, Org. Lett. 2006, 8, 741.
35. - elimination were also considered. The calculated activation barrier for pathways I and III for such possibilities are summarized in the Table S12 in the Supporting Information.
36. -1 at the PCM(THF)/ mPW1PW91/6-311G**//6-31G* level of theory for phenol-assisted (PA) and methanol-assisted (MA) pathways, respectively. For other transition-state models for various intermediates, barriers with respect to the corresponding hydrogen bonded complexes are provided in Tables S1-S3 and S13-S14 in the Supporting Information.
37. LUMO(acceptor)energy difference (eV) for pathways I to IV are calculated to be E1=2.6, E2=3.3, E3=1.5, and E4=2.8, respectively. See Figure S8 in the Supporting Information.
38. The summary of the charge distribution in all the transition states is provided in Figure S9 in the Supporting Information.
39. -1 lower with trans-iminuim ion at the PCM(THF)/mPW1PW91/6-311G**//6-31G* level of theory. The barriers are calculated by taking the lower energy trans-iminium ion as the reference point. We have attempted to locate the C-C bond formation TSs involving both cis and trans-MVK as well as the corresponding iminium ions. The TSs involving the trans-iminium ion in pathway III could not be identified at the PCM(THF)/mPW1PW91/6-31G* level of theory even after repeated attempts. A number of initial guess TS geometries differing in their relative orientations between the iminium ion and the enamine intermediates were considered. All such attempts failed to converge to a first-order saddle point. Information regarding transition states with trans-MVK or trans-iminium ion is provided in Figure S1 in the Supporting Information.
40. F. R. Clemente, K. N. Houk, Angew. Chem. 2004, 116, 5890;
41. Angew. Chem. Int. Ed. 2004, 43, 5766;
42. P. H.-Y. Cheong, K. N. Houk, J. Am. Chem. Soc. 2004, 126, 13912;
43. F. R. Clemente, K. N. Houk, J. Am. Chem. Soc. 2005, 127, 11294;
44. R. Gordillo, K. N. Houk, J. Am. Chem. Soc. 2006, 128, 3543;
45. C. B. Shinisha, R. B. Sunoj, Org. Bimol. Chem. 2007, 5, 1287;
46. M. P. Patil, R. B. Sunoj, Chem. Eur. J. 2008, 14, 10472.
47. For more details on the experimental conditions, such as the solvent systems employed, for organocatalyzed Michael addition reactions See Refs. [4], [5], [8].
48. The computed activation barriers as well as geometrical details of the TSs involving two phenol molecules are provided in Table S11 and Figure S5 in the Supporting Information, respectively. It is identified that the two phenol-assisted pathway is energetically slightly better compared to that with one phenol as well as the two methanol- assisted case. We have not been able to optimize these geometries in the PCM model owing to poor convergence issues. Therefore the Gibbs free energies of activation for this model could not be calculated.
49. The range of activation barriers for the unassisted 1,3-proton transfer was found to be nearly the same even with higher basis sets (6- 311+G**). See Table S5 in the Supporting Information
50. 7, are less than 150.08°). See Figure S2 in the Supporting Information.
51. The optimized transition state geometries are provided in Figure S3 in the Supporting Information. A summary of Mulliken and Natural (NPA) charges obtained at the PCM(THF)/mPW1PW91/6-311G**//6- 31G* as well as mPW1PW91/6-311G**//PCM(THF)/mPW1PW91/6- 31G* level of theory is provided in Figure S11 in the Supporting Information.
52. A related example on the role of explicit solvent (water) molecules in ammonia addition to formaldehyde can be found in I. H. Williams, D. Spangler, D. A. Femec, G. M. Maggiora, R. L. Schowen, J. Am. Chem. Soc. 1983, 105, 31;
53. I. H. Williams, D. Spangler, G. M. Maggiora, R. L. Schowen, J. Am. Chem. Soc. 1985, 107, 7717;
54. I. H. Williams, J. Am. Chem. Soc. 1987, 109, 6299.
55. -1 is predicted at the PCM(THF)/mPW1PW91/6- 311G**//6-31G* level for the second step PA-2I'. See Figure S3 in the Supporting Information for geometric details of the PA-2I'.
56. The gas-phase activation barriers computed by using different levels of theory for the unassisted pathway are provided in Table S4 in the Supporting Information.
57. We have earlier established that the amine-assisted pathways (for the addition as well as dehydration step) are less effective compared to the alcohol assisted pathways (See Ref. [11]). Therefore transition states, particularly for the dehydration step, stabilized by pyrrolidine molecules are not considered in the present investigation.
58. The pKa values for methanol and phenol are found to be 15.5 and 10.0, respectively, under aqueous conditions at 25°C;
59. J. J. Klicic, R. A. Friesner, S. Y. Liu, W. C. Guida, J. Phys. Chem. A 2002, 106, 1327.
60. -1 higher than with MA-2II at the PCM(THF)/B3LYP/6- 311G**//6-31G* level of theory.
61. -1 is predicted for the proton transfer step (PA-3I') at the PCM(THF)/mPW1PW91/6-311G**//6-31G * level. See Figure S4 in the Supporting Information for geometry details of the PA-3I'.
62. -1 at the PCM(THF)/mPW1PW91/6- 311G*//6-31G* level of theory.
63. Careful examination of the available literature conveys that iminium ion catalysis is generally carried out in the presence of compounds capable of hydrogen bonding, either in the form of catalyst or cocatalyst (additives). See Ref. [6] and references therein.
64. -), Lithium diisopropylamide (LDA), and triphenylmethyl anion.[34b] In the absence of strong bases, as in the present situation, the generation of an enolate ion is unlikely and hence the addition of an enolate ion to the iminium ion is much less likely to operate. The geometric details of the TSs for the addition of enolate to the iminium ion as well as to the MVK are provided in Figure S6 in the Supporting Information;
65. F. A. Carey, R. J. Sundberg, Advanced Organic Chemistry; Part B: Reaction and Synthesis, Kluwer Academic, New York, 2000.
66. The analysis on the basis of the available stationary points reveals that the trends in the UA and MA modes are likely to remain the same, as noticed in the case of PA mode.
67. J. P. Perdew, S. H. Chevary, K. A. Vosko, K. A. Jackson, M. R. Pederson, D. J. Singh, C. Fiolhais, Phys. Rev. B 1992, 46. 6671;
68. J. P. Perdew, S. H. Chevary, K. A. Vosko, K. A. Jackson, M. R. Pederson, D. J. Singh, C. Fiolhais, Phys. Rev. B 1993, 48, 4978;
69. J. P. Perdew, K. Burke, Y. Wang, Phys. Rev. B 1996, 54, 16533;
70. C. Adamo, V. Barone, J. Chem. Phys. 1998, 108, 664.
71. A. D. Becke, J. Chem. Phys. 1993, 98, 5648;
72. C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785.
73. M. Cossi, V. Barone, R. Cammi, J. Tomasi, Chem. Phys. Lett. 1996, 255, 327;
74. E. Cances, B. Mennucci, J. Tomasi, J. Chem. Phys. 1997, 107, 3032;
75. M. Cossi, G. Scalmani, N. Rega, V. Barone, J. Chem. Phys. 2002, 117, 43.
76. Gaussian 03 (Revision C.02), M. J. Frisch, G.W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgo- ACHTUNGTRENUNGmery, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R. E. tratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Nanayakkara, M.
77. H. L. Woodcock. H. F. Schaefer III, P. R. Schreiner, J. Phys. Chem. A 2002, 106, 11923;
78. P. R. Schreiner, A. A. Fokin, R. A. Pascal Jr. , A. de Meijere, Org. Lett. 2006, 8, 3635;
79. J. Zhao, D. G. Truhler, J. Chem. Theory Comput. 2007, 3, 289;
80. M. D. Wodrich, C. Corminboeuf, P. R. Schreiner, A. A. Fokin, P. v. R. Schleyer, Org. Lett. 2007, 9, 1851;
81. S. Grimme, M. Steinmetz, M. Korth, J. Chem. Theory Comput. 2007, 3, 42;
82. P. R. Schreiner, Angew. Chem. 2007, 119, 4295;
83. Angew. Chem. Int. Ed. 2007, 46, 4217.
84. Some select examples on the successful applications of the mPW1PW91 functional include A. Pelekh, R. W. Carr, J. Phys. Chem. A 2001, 105, 4697;
85. M. Porembski, J. C. Weisshaar, J. Phys. Chem. A 2001, 105, 6655;
86. R. A. Klein, B. Mennucci, J. Tomasi, J. Phys. Chem. A 2004, 108, 5851;
87. R. A. Klein, M. A. Zottala, Chem. Phys. Lett. 2006, 419, 254;
88. Y. Zhao, D. G. Truhlar, J. Phys. Chem. A 2004, 108, 6908;
89. S. S. Pinto, H. P. Diogo, R. C. Guedes, B. J. C. Cabral, M. E. M. da Piedade, A. M. Simoes, J. Phys. Chem. A 2005, 109, 9700.
90. J. B. Foresman, T. A. Keith, K. B. Wiberg, J. Snoonian, M. J. Frisch, J. Phys. Chem. 1996, 100, 16098;
91. Y. Takano, K. N. Houk, J. Chem. Theory Comput. 2005, 1, 70;
92. N. Sadlej-Sosnowska, Theor. Chem. Acc. 2007, 118, 281.
93. J. F. Austin, D. W. C. MacMillan, J. Am. Chem. Soc. 2002, 124, 1172;
94. F. Tanaka, R. Thayumanavan, N. Mase, C. F. Barbas III, Tetrahedron Lett. 2004, 45, 325;
95. P. M. Pihko, K. M. Laurikainen, A. Usano, A. I. Nyberg, J. A. Kaavi, Tetrahedron 2006, 62, 317;
96. N. Mase, R. Thayumanavan, F. Tanaka, C. F. Barbas III, Org. Lett. 2004, 6, 2527.
97. P. Claverie, J. P. Daudey, J. Langlet, B. Pullman, D. Piazzola, M. Duron, J. Phys. Chem. 1978, 82, 405;
98. J. R. Pliego Jr. , J. M. Riveros, J. Phys. Chem. 2001, 105, 7241;
99. Z. Cao, M. Lin, Q. Zhang, Y. Mo, J. Phys. Chem. A 2004, 108, 4277;
100. B. Balta, G. Monard, M. F. Ruiz-Lopez, M. Antonie, A. Gand, S. Boschi-Muller, G. Branlant, J. Phys. Chem. A 2006, 110, 7628;
101. C. M. Aikens, M. S. Gordon, J. Am. Chem. Soc. 2006, 128, 12635.
102. The activation energies obtained including electrostatic as well as non-electrostatic terms corresponding to cavitation, dispersion, and short-range repulsions are provided in Tables S8-S10 in the Supporting Information. The computed activation barriers exhibit the same trends as noticed with those consisting of only electrostatic terms. The relative preference of various pathways, a key point in the present study, is found to remain the same.
103. C. Gonzalez, H. B. Schlegel, J. Chem. Phys. 1989, 90, 2154;
104. C. Gonzalez, H. B. Schlegel, J. Phys. Chem. 1990, 94, 5523.
105. E. D. Glendening, A. E. Reed, J. E. Carpenter, F. Weinhold, NBO Version 3.1;
106. A. E. Reed, L. A. Curtiss, F. Weinhold, Chem. Rev. 1988, 88, 899.