An epoxide intermediate in nucleophilic acylations by thiazolium precursors

Organic Letters

Volumn 9, Issue 16, 2007, Pages 3065-3068

  Gronert, Scott ^a  

^a VIRGINIA COMMONWEALTH UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 34547926884     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol0711467     Document Type: Article

References (19)

1. Mattson, A. E.; Zuhl, A. M.; Reynolds, T. E.; Scheidt, K. A. J. Am. Chem. Soc. 2006, 128, 4932.
2. Mattson, A. E.; Scheidt, K. A. J. Am. Chem. Soc. 2007, 129, 4508.
3. Breslow, R.; Schmuck, C. Tetrahedron Lett. 1996, 37, 8241.
4. Breslow, R. J. Am. Chem. Soc. 1958, 80, 3719.
5. Mattson, A. E.; Bharadwaj, A. R.; Zuhl, A. M.; Scheidt, K. A. J. Org. Chem. 2006, 71, 5715.
6. Johnson, J. S. Angew. Chem., Int. Ed. 2004, 43, 1326.
7. Christmann, M. Angew. Chem., Int. Ed. 2005, 44, 2632.
8. de Alaniz, J. R.; Rovis, T. J. Am. Chem. Soc. 2005, 127, 6284.
9. Myers, M. C.; Bharadwaj, A. R.; Milgram, B. C.; Scheidt, K. A. J. Am. Chem. Soc. 2005, 127, 14675.
10. Chan, A.; Scheidt, K. A. J. Am. Chem. Soc. 2006, 128, 4558.
11. Stetter, H. Angew. Chem., Int. Ed. Engl. 1976, 15, 639.
12. Seebach, D. Angew. Chem., Int. Ed. Engl. 1979, 18, 239.
13. Calculations were completed at the MP2/6-31+G(d,p) level. When there was a possibility of multiple rotamers, preliminary calculations at lower levels were used to identify the most stable one for the higher-level calculations. Reported energies include zero-point vibrational energy corrections from HF/6-31+G(d,p) calculations scaled by 0.9135 (see ref 15). AU species exhibited the proper number of imaginary frequencies. Energies do not contain thermal corrections.
14. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, revision C.02; Gaussian, Inc.; Wallingford, CT, 2004.
15. Scott, A. P.; Radom, L. J. Phys. Chem. 1996, 100, 16502.
16. Solvation will favor 1 because it is a zwitterion with a large dipole moment. To crudely estimate the effect, an aqueous solvation calculation using the SM5 model was completed at the MP2/6-31+G(d) level. The energetic advantage of 3 over 1 is reduced to almost zero in this model of aqueous solution. In a less polar solvent such as dichloromethane, one would expect 3 to dominate.
17. Aqueous solvation energies were computed in Spartan 02 using Cramer and Truhlar's SM5 approach in conjunction with MP2/6-31+G(d) calculations: Johnson, J. A.; Deppmeir, B. J.; Driessen, A. J.; Hehre, W. J.; Klunzinger, P. B.; Pham, I. N.; Wantanabe, M. Spartan 02, 1.0.8; Wavefunction: Irvine, CA, 2002.
18. Calculations at the HF level indicate that complexation of 6 with 7 provides 8 kcal/mol of stabilization in the gas phase. This is a crude measure of the barrier reduction. At the MP2 level, the complex reverts to 3 and 5 without a barrier.
19. A unimolecular rearrangement from 1 to 7 to 4 was calculated. The barriers are high (7.5 and 19.3 kcal/mol relative to 1). See Supporting Information.