Evidence for involvement of cationic intermediate in epoxidation of chiral allylic alcohols and unfunctionalised alkenes catalysed by MnIII(quinazolinone) complexes
Tetrahedron, cilt.74, sa.1, ss.49-57, 2018 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 74 Sayı: 1
- Basım Tarihi: 2018
- Doi Numarası: 10.1016/j.tet.2017.11.034
- Dergi Adı: Tetrahedron
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Sayfa Sayıları: ss.49-57
- Atatürk Üniversitesi Adresli: Evet
Özet
A pair of Mn-III(quinazolinone) complexes was prepared and evaluated in the catalytic epoxidation of the chiral allylic alcohols and unfunctionalised alkenes with iodosylbenzene. Epoxidation of chiral allylic alcohols with 1,3-allylic strain proceeded chemo- and diastereoselectively to give threo-epoxy alcohol (up to 99% d.r). Epoxidation of unfunctionalised alkenes by the proposed catalyst system proceeded nonselectively, as evidenced by the formation of isomerization and rearrangement products in the epoxidation of (Z)-stilbene. A three-step pathway involving a cationic intermediate is proposed for the formation of isomerization and rearrangement products. The fact that only products resulting from the cationic intermediate were detected in the oxidation of a mechanistic probe, (2-methoxy-3-vinylcyclopropyl)benzene, with Mn-III(quinazolinone) and PhIO substantiated the cationic oxygen transfer mechanism. (C) 2017 Elsevier Ltd. All rights reserved.