Collect. Czech. Chem. Commun. 2008, 73, 786-794
https://doi.org/10.1135/cccc20080786

The Concerted Nature of the Enzymatic Cyclization of Rings A-D of Squalene to Hopene

B. Andes Hess, Jr.a,* and Lidia Smenteka,b

a Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, U.S.A.
b Institute of Physics, N. Copernicus University, 87-100 Toruń, Poland

References

1a. Wendt K. U., Schulz G. E, Corey E. J., Liu D. R.: Angew. Chem. Int. Ed. 2000, 39, 2812. <https://doi.org/10.1002/1521-3773(20000818)39:16<2812::AID-ANIE2812>3.0.CO;2-#>
1b. Yoder R. A., Johnston J. N.: Chem. Rev. 2005, 105, 4730. <https://doi.org/10.1021/cr040623l>
1c. Xu R., Fazio G. C., Matsuda S. P. T.: Phytochemistry 2004, 65, 261. <https://doi.org/10.1016/j.phytochem.2003.11.014>
1d. Wendt K. U.: Angew. Chem. Int. Ed. 2005, 44, 3966. <https://doi.org/10.1002/anie.200500804>
1e. Abe I.: Nat. Prod. Rep. 2007, 24, 1311. <https://doi.org/10.1039/b616857b>
2. Reinert D. J., Balliano G., Schulz G. E.: Chem. Biol. 2004, 11, 121. <https://doi.org/10.1016/j.chembiol.2003.12.013>
3. The fourth one is that of cation-π interactions within the enzyme cavitiy, which is not discussed here. See: Morikubo N., Fukuda Y., Ohtake K., Shinya N., Kiga D., Sakamoto K., Asanuma M., Hirota H., Yokoyama S., Hoshino T.: J. Am. Chem. Soc. 2006, 128, 13184. <https://doi.org/10.1021/ja063358p>
4a. Matsuda S. P. T., Wilson W. K.: Org. Biomol. Chem. 2006, 4, 530. <https://doi.org/10.1039/b513599k>
4b. Xiong W. K., Rocco F., Wilson W. K., Xu R., Ceruti M., Matsuda S. P. T.: J. Org. Chem. 2005, 70, 5362. <https://doi.org/10.1021/jo050147e>
5. Calculations were performed with the DFT method using: Frisch M. J., Trucks G. W., Schlegel H. B., Scuseria G. E., Robb M. A., Cheeseman J. R., Zakrzewski V. G., Montgomery J. A., Jr., Stratmann R. E., Burant J. C., Dapprich S., Millam J. M., Daniels A. D., Kudin K. N., Strain M. C., Farkas O., Tomasi J., Barone V., Cossi M., Cammi R., Mennucci B., Pomelli C., Adamo C., Clifford S., Ochterski J., Petersson G. A., Ayala P. Y., Cui Q., Morokuma K., Malick D. K., Rabuck A. D., Raghavachari K., Foresman J. B., Cioslowski J., Ortiz J. V., Stefanov B. B., Liu G., Liashenko A., Piskorz P., Komaromi I., Gomperts R., Martin R. L., Fox D. J., Keith T., Al-Laham M. A., Peng C. Y., Nanayakkara A., Gonzalez C., Challacombe M., Gill P. M. W., Johnson B., Chen W., Wong M. W., Andres J. L., Gonzalez C., Head-Gordon M., Replogle E. S., Pople J. A.: Gaussian 98W. Gaussian, Inc., Pittsburgh (PA) 1998. Becke’s three-parameter hybrid method (ref.5) with the Lee–Yang–Parr correlation function (ref.6) and the 6-31G* basis set (ref.7) were employed.
6. Becke A. D.: J. Chem. Phys. 1993, 98, 5648. <https://doi.org/10.1063/1.464913>
7. Lee C, Yang W, Parr R. G.: Phys. Rev. B 1988, 37, 785. <https://doi.org/10.1103/PhysRevB.37.785>
8. Hariharan P. C, Pople J. A.: Theor. Chim. Acta 1973, 28, 213. <https://doi.org/10.1007/BF00533485>
9. Calculation of the second derivative of the energy of 2 confirmed it to be a minimum on the potential surface.
10. Hess B. A., Jr., Smentek L.: Org. Lett. 2004, 6, 1717. <https://doi.org/10.1021/ol0496125>
11. Hess B. A., Jr.: Org. Lett. 2003, 5, 165. <https://doi.org/10.1021/ol027449c>
12. Hess B. A., Jr.: J. Am. Chem. Soc. 2002, 124, 10286. <https://doi.org/10.1021/ja026850r>
13. In the recent report: Vrcek V.: Int. J. Quantum Chem. 2007, 107, 1772, it has been shown that there are other possible rearrangement pathways for carbocation 20; however, these are unlikely to play a role in the cyclization of squalene because of conformational effects, which are so important in the enzyme catalyzed cyclization of squalene. <https://doi.org/10.1002/qua.21258>
14. Morikubo N., Fukuda Y., Ohtake K., Shinya N., Kiga D., Sakamoto K., Asanuma M., Hirota H., Yokoyama S., Hoshino T.: J. Am. Chem. Soc. 2006, 128, 13184. <https://doi.org/10.1021/ja063358p>