シライ　トモヒコ   Shirai Tomohiko   白井　智彦    所属   東邦大学  理学部 化学科    職種   講師
論文種別	原著
言語種別	英語
査読の有無	査読あり
表題	Scope and Mechanistic Studies of the Cationic Ir/Me-BIPAM-Catalyzed Asymmetric Intramolecular Direct Hydroarylation Reaction
掲載誌名	正式名：Organometallics ISSNコード：0276-7333/1520-6041
掲載区分	国外
出版社	ACS
巻・号・頁	34(14),pp.3459-3463
著者・共著者	T. Shirai,Y. Yamamoto
担当区分	筆頭著者
発行年月	2015/07
概要	Results of mechanistic studies on asymmetric hydroarylation of alpha-keto amides Via direct C-H bond addition to a carbonyl group catalyzed by a cationic Ir/Me-BIPAM complex are presented in this paper. A catalytic cycle involving C-H bond cleavage to give an Ar-[Ir](+) intermediate, insertion of a carbonyl group into the aryl-iridium bond, giving iridium alkoxide, and finally reductive elimination to reproduce active [Ir](+) species is proposed. The mechanistic insight for the iridium hydride species indicated that the C-H bond cleavage is caused in a reversible manner. Furthermore, the kinetic isotope effect was measured by product analysis of the reaction to compare HID, and it was determined that k(H)/k(D) was 1.85. These experimental results suggest that the C-H bond cleavage step is not included hi the turnover-limiting step. In addition, Hammett studies of substrates (rho = -0.99) demonstrated that electron-donating groups at the para position to the reactive C-H bond accelerate the reaction rate. This linear relationship obtained in the Hammett plot indicates that the nucleophilicity of the aryl-iridium intermediate is an important factor in this reaction. All of the data indicate that carbonyl insertion into aryl-iridium is included in the turnover-limiting step of the catalytic cycle.
DOI	10.1021/om501260w