翻訳と辞書 Words near each other ・ Heterixalus alboguttatus ・ Heterixalus andrakata ・ Heterixalus betsileo ・ Heterixalus boettgeri ・ Heterixalus carbonei ・ Heterixalus luteostriatus ・ Heterixalus madagascariensis ・ Heterixalus punctatus ・ Heterixalus rutenbergi ・ Heterixalus tricolor ・ Heterixalus variabilis ・ Hetero (disambiguation) ・ Hetero Drugs ・ Hetero-Genesys Laboratory ・ Heteroatom ・ Heteroatom-promoted lateral lithiation ・ Heteroazeotrope ・ Heterobapta ・ Heterobasidiomycetes ・ Heterobasidion ・ Heterobasidion annosum ・ Heterobasidion irregulare ・ Heterobasidion occidentale ・ Heterobathmia diffusa ・ Heterobathmia pseuderiocrania ・ Heterobathmia valvifer ・ Heterobathmioidea ・ Heteroblasty (botany) ・ Heterobostrychus ・ Heterobranchia Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Heteroatom-promoted lateral lithiation ： ウィキペディア英語版 Heteroatom-promoted lateral lithiation Heteroatom-promoted lateral lithiation is the site-selective replacement of a benzylic hydrogen atom for lithium for the purpose of further functionalization. Heteroatom-containing substituents may direct metalation to the benzylic site closest to the heteroatom or increase the acidity of the ring carbons via an inductive effect.〔Clark, R. D.; Jahangir, A. ''Org. React.'' 1995, ''47'', 1. 〕 ==Introduction== Toluene derivatives with heteroatom-containing substituents in the ''ortho'' position undergo site-selective benzylic lithiation in the presence of organolithium compounds (either alkyllithiums or lithium dialkylamides). Coordination of the Lewis acidic lithium atom to the Lewis basic heteroatom, as well as inductive effects derived from the electronegativity of the heteroatom, encourage selective deprotonation at the benzylic position.〔 Competitive ring metalation (directed ''ortho''-metalation) is an important side reaction, but a judicious choice of base often allows for selective benzylic metalation. Useful heteroatom-containing directing groups include dialkylamines,〔Jones, F. N.; Zinn, M. F.; Hauser, C. R. ''J. Org. Chem.'' 1963, ''28'', 663.〕 amides (secondary or tertiary), ketone enolates,〔Klein, J.; Medlik-Balan, A. ''J. Org. Chem.'' 1976, ''41'', 3307.〕 carbamates, and sulfonates. Lateral lithiation of alkyl-substituted heterocycles incorporating heteroatom-containing substituents is also possible, although ring lithiation α to the ring heteroatom may compete with lateral lithiation.〔 The products of lateral lithiation react with a variety of electrophiles, including reactive alkyl halides (allylic, benzylic, and primary), carbonyl compounds, silyl and stannyl chlorides, disulfides and diselenides, and others. A general, highly selective method for benzylic metalation using a mixed lithium and potassium metal amide (LiNK chemistry) has been developed which permits metalation regardless of the relative position (''ortho'', ''meta'' or ''para'') of the methyl group to the heteroatom containing substituent 〔Fleming P.; O'Shea D.F. J. Am. Chem. Soc. 2011, 133, 1698.〕 ''(1)''File:LatLithGen.png 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Heteroatom-promoted lateral lithiation」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.