Isoprene-catalyzed lithiation of imidazole: synthesis of 2-(hydroxyalkyl)- and 2-(aminoalkyl)imidazoles
作者:Rosario Torregrosa、Isidro M. Pastor、Miguel Yus
DOI:10.1016/j.tet.2005.09.024
日期:2005.11
of isoprene (20 mol%) in THF at room temperature. By reacting this organolithium with carbonyl electrophiles 2-(hydroxyalkyl)imidazoles 3 were obtained, in good yields. As a result of the reaction of the mentioned lithium intermediate with imines 4, the corresponding 2-(aminoalkyl)imidazoles 5 were isolated in excellent yields.
readily available from iminoether hydrochlorides and acid chlorides. According to a more general route towards these doubly activated dienes, N-trialkylsilylimidates and N-trialkylsilylimines derived from non-enolizable aldehydes were conveniently converted in a one-pot sequence into the corresponding azadienes by reaction with an acid chloride in the presence of triethylamine. Finally, cyclic dienes could
已经通过三种途径制备了在C-3处带有活化三烷基甲硅烷基氧基的2-Aza-1,3-二烯。第一条途径涉及N-酰基酰亚胺的甲硅烷基化,其可从亚氨基醚盐酸盐和酰氯容易获得。根据朝向这些双活化二烯的更通用的途径,通过在三乙胺的存在下与酰氯反应,将由不可烯化的醛衍生的N-三烷基甲硅烷基酰亚胺酯和N-三烷基甲硅烷基亚胺方便地以一锅法转化为相应的氮杂二烯。最后,可以通过在三乙胺的存在下用三烷基甲硅烷基三氟甲磺酸酯在两个氧上将戊二酰亚胺直接甲硅烷基化来制备环状二烯。2-氮二烯的构型和构象已由1 H,13确定C和15 N NMR光谱。
Trans -Diastereoselective synthesis of 3-phthalimido β-lactams via a two step-staudinger reaction
Hetero [4 + 2] Cycloadditions of (Trialkylsilyl)vinylketenes. Synthesis of α,β-Unsaturated δ-Valerolactones and -Lactams
作者:Dawn M. Bennett、Iwao Okamoto、Rick L. Danheiser
DOI:10.1021/ol9907217
日期:1999.8.1
[formula: see text] HeteroDiels-Alderreactions of (trialkylsilyl)vinylketenes (TAS-vinylketenes) with carbonyl and imino dienophiles are described. TAS-vinylketenes participate as electron-rich dienes in [4 + 2] cycloadditions with diethyl ketomalonate to afford alpha,beta-unsaturated delta-valerolactones in good yield. Nonenolizable N-alkyl- and N-(trimethylsilyl)imines combine with TAS-vinylketenes
Lewis acid-catalyzed cyclization of 2-aza-3-trimethylsilytoxy-buta-1,3-diene is reported.. Stereochemical differences with the uncatalyzed cyclization are discussed. (C) 2003 Elsevier Science Ltd. All rights reserved.