Theoretical Studies on the Mechanism of the Formation of Cyclopentadienes and Dihydropyridazines
CHEMISTRYSELECT, cilt.6, sa.37, ss.9806-9813, 2021 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 6 Sayı: 37
- Basım Tarihi: 2021
- Doi Numarası: 10.1002/slct.202102928
- Dergi Adı: CHEMISTRYSELECT
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier
- Sayfa Sayıları: ss.9806-9813
- Anahtar Kelimeler: 1, 3-hydrogen shift, cycloaddition, cyclopentadiene, density functional calculations, dihydropyridazines, retro-Diels-Alder, tetrazines, DIELS-ALDER REACTION, THERMOCHEMISTRY, CYCLOADDITION, DERIVATIVES, ACTIVATION, COMPLEXES, CHEMISTRY, KINETICS, LIGANDS
- Atatürk Üniversitesi Adresli: Evet
Özet
The synthesis of cyclopentadiene derivatives via the domino reaction of norbornadienes with dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate, followed a retro-Diels-Alder reaction, was reported by Dalkilic few years ago (Tetrahedron 2015;71 : 1966). In some cases, the formation of an unexpected dihydropyridazine (DHP) was observed, and explained by a 1,3-hydrogen shift. A density functional theory study is herein reported giving insights into the proposed mechanisms with different substituents on norbornadiene. Based on the kinetic and thermodynamic data, the retro-Diels-Alder reaction is confirmed to explain the formation of cyclopentadienes plus pyridazines. The intramolecular 1,3-hydrogen shift mechanism was not sufficient to explain the exclusive formation of two DHPs. Thus, an alternative mechanism involving a stepwise tautomerisation is being reported for formation of DHPs.