Diastereoselective Ti-mediated preparation of bicyclic aminocyclopropanes from N-alkenyl amides
摘要:
Intramolecular Ti-mediated alkene-amide couplings of a range of N-alk-3-enyl amides fitted with a substituent at the homoallylic position are described. CF3-substituted compounds are suitable substrates and bicyclic aminocyclopropanes bearing a CF3 group can be prepared in this way. Good diastereoselectivities can be observed depending on the substitution pattern, and best results are obtained in diethyl ether rather than in THF. (C) 2009 Elsevier Ltd. All rights reserved.
Ti-mediated intramolecular cyclopropanation of N-alkenyl thioamides: scope and mechanistic study
作者:Fabien Hermant、Emmanuel Nicolas、Yvan Six
DOI:10.1016/j.tet.2014.04.006
日期:2014.6
Although thioamides generally undergo a reductive alkylation process when they are treated with a Grignard reagent in the presence of Ti(OiPr)(4), substrates fitted with a but-3-enyl substitution at the nitrogen atom are shown to be converted into bicyclic aminocyclopropanes. These reactions are compared with the similar cyclisations of the corresponding carboxylic amide substrates. A mechanistic study is provided. Coincidently, new reagent systems are identified for the mediation of the same transformation. (C) 2014 Elsevier Ltd. All rights reserved.