The photochemical nucleophile-olefin combination, aromatic substitution reaction: Methanol-monoterpenes, 1,4-dicyanobenzene.
Date
1992
Authors
Du, Xinyao.
Journal Title
Journal ISSN
Volume Title
Publisher
Dalhousie University
Abstract
Description
The photo-induced electron transfer reaction between 1,4-dicyanobenzene (1) and 2,3-dimethyl-2-butene (7) in acetonitrile-methanol solution leads to the 1:1:1 adduct 8. This type of reaction, the photo-NOCAS reaction, has been extended to other acceptor/donor systems. Fur unsymmetric olefins, the formation of anti-Markovnikov products is favored.
As part of a program to define the scope of the photo-NOCAS reaction, the dicyanobenzene/vinylcyclobutane (14, 15) and dicyanobenzene/vinylcyclopropane (64) systems have been examined in this study. The four-membered rings of the initially formed radical cations from both $\alpha$-pinene (14) and $\beta$-pinene (15) cleave to give the distonic radical cations having the tertiary cation - allylic radical structure (29, 31). These radical cations either react with methanol, finally leading to photo-NOCAS products, or are trapped by acetonitrile, giving rise to the cyclic imines (19, 23). On the other hand, the initially formed radial cations from 2-carene (64) rapidly reacts with methanol before the three-membered ring cleaves completely.
The possible connection between 14$\sp{+.}$ and the radical cation of tricyclene (33) has also been investigated. The radical cation of tricyclene is relatively stable; the nucleophilic opening of the three-membered ring has been observed. No evidence was found for the ring-opening of 33$\sp{+.}$ to give the distonic radical cation 29.
By the study of the photo-NOCAS reactions with nopol (52) and 2-(1-cyclohexenyl)ethanol (57), a comparison was made between the ring-opening and the intramolecular and intermolecular nucleophilic reaction of the radical cation(s).
Ab initio calculations at the STO-3G level were performed on most of the radical cations involved in this study and the calculations were compared with the experimental results. Moreover, a detailed ab initio study at higher levels on the two model systems, 1-butene (46) and 4,4-dimethyl-1-pentene (47), shows the profound effects of the two geminal methyl groups on the energetics for the cleavage process of the radical cations involved. The calculations were also carried out on the interaction between the allyl and alkyl radical and carbocation moieties.
Thesis (Ph.D.)--Dalhousie University (Canada), 1992.
As part of a program to define the scope of the photo-NOCAS reaction, the dicyanobenzene/vinylcyclobutane (14, 15) and dicyanobenzene/vinylcyclopropane (64) systems have been examined in this study. The four-membered rings of the initially formed radical cations from both $\alpha$-pinene (14) and $\beta$-pinene (15) cleave to give the distonic radical cations having the tertiary cation - allylic radical structure (29, 31). These radical cations either react with methanol, finally leading to photo-NOCAS products, or are trapped by acetonitrile, giving rise to the cyclic imines (19, 23). On the other hand, the initially formed radial cations from 2-carene (64) rapidly reacts with methanol before the three-membered ring cleaves completely.
The possible connection between 14$\sp{+.}$ and the radical cation of tricyclene (33) has also been investigated. The radical cation of tricyclene is relatively stable; the nucleophilic opening of the three-membered ring has been observed. No evidence was found for the ring-opening of 33$\sp{+.}$ to give the distonic radical cation 29.
By the study of the photo-NOCAS reactions with nopol (52) and 2-(1-cyclohexenyl)ethanol (57), a comparison was made between the ring-opening and the intramolecular and intermolecular nucleophilic reaction of the radical cation(s).
Ab initio calculations at the STO-3G level were performed on most of the radical cations involved in this study and the calculations were compared with the experimental results. Moreover, a detailed ab initio study at higher levels on the two model systems, 1-butene (46) and 4,4-dimethyl-1-pentene (47), shows the profound effects of the two geminal methyl groups on the energetics for the cleavage process of the radical cations involved. The calculations were also carried out on the interaction between the allyl and alkyl radical and carbocation moieties.
Thesis (Ph.D.)--Dalhousie University (Canada), 1992.
Keywords
Chemistry, Organic.