Investigation of Computational Reaction Mechanism for The Formation of The 6-endo Cyclization Product of 1- Vinyl 5-Hexenyl Radicals

Öz

A computational study for reaction mechanism of 1-vinyl 5-hexenyl radicals is carried out using the density functional theory. The results showed that the reaction for the formation of thermodynamically stable 6-endo-trig cyclization product can progress over both 6-endo-trig and 5-exo-trig cyclization. Moreover, our computations demonstrated that when 5-exo-trig cyclization intermediate is stable, 5-exo-trig cyclization mode would be responsible for the formation of the 6-endo-trig cyclization product.

Anahtar Kelimeler

• Baldwin’s rules
• Cyclization
• Vinyl radical
• Iminyl radical
• Density functional theory
• Computational chemistry

1-Vinil 5-Heksenil Radikallerinin 6-endo Siklizasyon Ürününün Oluşumu için Hesaplamalı Reaksiyon Mekanizmasının İncelenmesi

Öz

1-Vinil 5-heksenil radikallerinin reaksiyon mekanizması için hesaplamalı bir çalışma, yoğunluk fonksiyonel teorisi kullanılarak gerçekleştirildi. Sonuçlarımız, termodinamik olarak kararlı 6-endo-trig halka kapanma ürününün oluşumuna yönelik reaksiyonun hem 5-ekso-trig hem de 6-endo-trig halka kapanma modları üzerinden ilerleyebileceğini gösterdi. Ayrıca, hesaplamalarımız, 5-ekso-trig halka kapanma ara ürününün kararlı olması durumunda, 6-endo-trig halka kapanma ürününün oluşumundan 5-ekso-trig modun sorumlu olacağını gösterdi.

Anahtar Kelimeler

• Baldwin kuralları
• Halka kapanma
• Vinil radikali
• İminil radikali
• Yoğunluk foksiyonel teori
• Hesaplamalı kimya

Teşekkür

Yazar desteği için Hakkari Üniversitesi'ne teşekkür eder.

Kaynakça

1. Beckwith, A. L. J., & O’Shea, D. M. (1986). Kinetics and mechanism of some vinyl radical cyclisations. Tetrahedron Letters, 27(38), 4525-4528.
2. Chatgilialoglu, C., Ferreri, C., Lucarini, M., Venturini, A. & Zavitsas, A. A. (1997). 5-exo-trig Versus 6-endo-trig c yclization of alk-5-enoyl radicals: the role of one-carbon ring expansion. Chemistry-A European Journal, 3(3), 376-387.
3. Curran, D. P., & Kuo, S. C. (1987). The tandem radical cyclization approach to angular triquinanes. Model studies and the total synthesis of (±)-Silphiperfolene and (±)-9-Episilphiperfolene. Tetrahedron, 43(20), 5653-5661.
4. Frisch, M. J., Trucks, G. W., Schlegel, H. B., Scuseria, G. E., Robb, M. A., Cheeseman, J. R., & Fox, D. J. (2019). Gaussian 16, Revision C.01, Gaussian Inc. Wallingford CT.
5. Gilmore, K., & Alabugin, I. V. (2011). Cyclizations of alkynes: revisiting baldwin’s rules for ring closure. Chemical Reviews, 111(11), 6513-6556.
6. Gomez, A. M., Company, M. D., Uriel, C., Valverde, S., & Lopez, J. C. (2007). 6-endo Versus 5-exo radical cyclization: Streamlined syntheses of carbahexopyranoses and derivatives by 6-endo-trig radical cyclization. Tetrahedron Letters, 48(9), 1645-1649.
7. Hariharan, P. C., & Pople, J. A. (1973). The influence of polarization functions on molecular orbital hydrogenation energies. Theoretica Chimica Acta, 28, 213-222.
8. Krishnan, R., Binkley, J. S., Seeger, R., & Pople, J. A. (1980). Self-consistent molecular orbital methods. XX. A basis set for correlated wave functions. Journal Chemical Physics, 72(1), 650-654.

9. Liao, J., Yang, X., Ouyang, L., Lai, Y., Huang, J., & Luo, R. (2021). Recent advances in cascade radical cyclization of radical acceptors for the synthesis of carbo- and heterocycles. Organic Chemistry Frontier, 8(6), 1345-1363.
10. Maust, M. C., Hendy, C. M., Jui, N. T., & Blakey, S. B. (2022). Switchable regioselective 6-endo or 5-exo radical cyclization via photoredox catalysis. Journal of the American Chemical Society, 144(9), 3776-3781.
11. McLean, A. D., & Chandler, G. S. (1980). Contracted gaussian basis sets for molecular calculations. I. Second row atoms Z=11-18. Journal Chemical Physics 1980; 72 (10): 5639-5648.
12. Rashatasakhon, P., Ozdemir, A. D., Willis, J., & Padwa, A. (2004). Six- versus five-membered ring formation in radical cyclizations of 7-bromo-substituted hexahydroindolinones. Organic Letters, 6(6), 917-920. Stork, G., & Mook, R. (1986). Five vs six membered ring formation in the vinyl radical cyclization. Tetrahedron Letters, 27(38), 4529-4532.
13. Tucker, J. W., & Stephenson, C. R. J. (2011). Tandem visible light-mediated radical cyclization-divinylcyclopropane rearrangement to tricyclic pyrrolidinones. Organic Letters, 13(20), 5468-5471.
14. Yang, D., Gu, S., Yan, Y. L., Zhao, H. W., & Zhu, N. Y. (2002). Atom-transfer tandem radical cyclization reactions promoted by lewis acids. Angewandte Chemie International Edition, 41(16), 3014-3017.
15. Zhao, Y., & Truhlar, D. G. (2008). The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: Two new functionals and systematic testing of four M06-class functionals and 12 other functionals. Theoretical Chemistry Accounts, 120, 215-241.