翻訳と辞書 Words near each other ・ 4'-Aminopropiophenone ・ 4'-demethylrebeccamycin synthase ・ 4'-Fluoro-α-pyrrolidinooctanophenone ・ 4'-Fluoro-α-pyrrolidinopentiophenone ・ 4'-Hydroxyisoflavone methyltransferase ・ 4'-Methoxy-α-pyrrolidinopentiophenone ・ 4'-Methoxy-α-pyrrolidinopropiophenone ・ 4'-methoxyisoflavone 2'-hydroxylase ・ 4'-Methyl-α-pyrrolidinobutiophenone ・ 4'-Methyl-α-pyrrolidinohexiophenone ・ 4'-Methyl-α-pyrrolidinopropiophenone ・ 4'-O-glucoside ・ 4'-phosphopantetheinyl transferase ・ 4+1 architectural view model ・ 4+1 Ensemble ・ 4+3 cycloaddition ・ 4+4 Photocycloaddition ・ 4, 3, 2, 1 ・ 4, 3, 2, 1 (k-os song) ・ 4, 3, 2, 1 (LL Cool J song) ・ 4, 5 and 6 ・ 4, 5, 6 ・ 4,000 Weeks' Holiday ・ 4,16-Androstadien-3β-ol ・ 4,21-Dehydrogeissoschizine ・ 4,4'-Azobis(4-cyanopentanoic acid) ・ 4,4'-Biphenol ・ 4,4'-Bipyridine ・ 4,4'-Diapophytoene desaturase ・ 4,4'-Diapophytoene synthase 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 4+3 cycloaddition ： ウィキペディア英語版 4+3 cycloaddition A () Cycloaddition is a cycloaddition between a 4 atom pi-system and a 3 atom pi-system to form a seven-membered ring. Allyl or oxyallyl cations (propenylium-2-olate) are commonly used 3 atom pi-systems, while a diene (such as butadiene) plays the role of the 4 atom pi-system. It represents one of the relatively few synthetic methods available to form seven-membered rings stereoselectively in high yield.〔Rigby, J. H.; Pigge, F. C. ''Org. React.'' 1997, ''51'', 351. 〕 The reaction is a topic academic research. ==Introduction== Symmetry-allowed () cycloaddition is an attractive method for the formation of historically difficult-to-access seven-membered rings. Neutral dienes and cationic allyl systems (most commonly oxyallyl cations) may react in a concerted or stepwise fashion to give seven-membered rings. A number of dienes have been employed in the reaction, although cyclic, electron-rich dienes such as those found in the pyrrole and furan ring systems are the best 4π systems for this process. Intramolecular variants are also efficient.〔Harmata, M.; Elahmad, S.; Barnes, C. L. ''Tetrahedron Lett.'' ''1995'', 36, 1397.〕 ''(1)''File:43Gen.png Recent developments have focused on expanding the scope of enantioselective () cycloadditions and the range of conditions available for generating the key oxyallyl cation (propenylium-2-olate) intermediate. 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「4+3 cycloaddition」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.