Aryl-substituted dimethylbenzimidazolines as effective reductants of photoinduced electron transfer reactions

被引：27

作者：

Hasegawa, Eietsu ^{[1
]}

Ohta, Taku ^{[1
]}

Tsuji, Shiori ^{[1
]}

Mori, Kazuma ^{[1
]}

Uchida, Ken ^{[1
]}

Miura, Tomoaki ^{[1
]}

Ikoma, Tadaaki ^{[1
,2
,3
]}

Tayama, Eiji ^{[1
]}

Iwamoto, Hajime ^{[1
]}

Takizawa, Shin-ya ^{[4
]}

Murata, Shigeru ^{[4
]}

机构：

[1] Niigata Univ, Fac Sci, Dept Chem, Nishi Ku, Niigata 9502181, Japan

[2] Niigata Univ, Ctr Instrumental Anal, Nishi Ku, Niigata 9502181, Japan

[3] Japan Sci & Technol Agcy, Core Res Evolutionary Sci & Technol, Kawaguchi, Saitama 3320012, Japan

[4] Univ Tokyo, Dept Basic Sci, Grad Sch Arts & Sci, Meguro Ku, Tokyo 1538902, Japan

来源：

TETRAHEDRON | 2015年 / 71卷 / 34期

基金：

日本科学技术振兴机构;

关键词：

Photoinduced electron transfer; 2-Aryl-1,3-dimethylbenzimidazoline; Epoxy ketone ring-opening; Radical rearrangement; Desulfonylation; Allylation; BETA-KETO-ESTERS; RADICAL RING-EXPANSION; CARBON-HYDROGEN BONDS; VISIBLE-LIGHT PHOTOCATALYSIS; N-TYPE DOPANT; PHOTOREDOX CATALYSIS; ALPHA; BETA-EPOXY KETONES; FORMAL TRANSFERS; REDUCTIVE TRANSFORMATION; ATTEMPTED GENERATION;

D O I：

10.1016/j.tet.2015.06.071

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

Photoinduced electron transfer (PET) reactions promoted by 2-aryl substituted 1,3-dimethylbenzimidazolines (Ar-DMBIH) were investigated. Excited states of Ar-DMBIH, formed by irradiation using light above 360 initiate PET reductions of various organic substrates, including transformations of epoxy ketones to aldols, free radical rearrangements such as the Dowd-Beckwith ring-expansion and 5-exo hexenyl cyclization, deprotection of N-sulfonyl-indols, and allylation of acyl formates. In these processes, Ar-DMBIH possessing 1-naphthyl, 2-naphthyl, 1-pyrenyl and 9-anthryl substituents formally act as two electron and one proton donors while the hydroxynaphthyl substituted derivative serves as a two electron and two proton donor. On the basis of the results of absorption spectroscopy studies, cyclic voltammetry and DFT calculation, a mechanistic sequence for these reduction reactions is proposed that involves initial photoexcitation of the aryl chromophore of the Ar-DMBIH followed by single electron transfer (SET) to the organic substrate to generate the radical cation of benzimidazoline and the radical anion of the substrate. (C) 2015 Elsevier Ltd. All rights reserved.

引用

页码：5494 / 5505

页数：12