Catalytic Asymmetric Synthesis of Cyclohexanes by Hydrogen Borrowing Annulations
作者:Roly J. Armstrong、Wasim M. Akhtar、Tom A. Young、Fernanda Duarte、Timothy J. Donohoe
DOI:10.1002/anie.201907514
日期:2019.9.2
Hydrogen borrowing catalysis serves as a powerful alternative to enolate alkylation, enabling the direct coupling of ketones with unactivated alcohols. However, to date, methods that enable control over the absolute stereochemical outcome of such a process have remained elusive. Here we report a catalytic asymmetric method for the synthesis of enantioenriched cyclohexanes from 1,5‐diols via hydrogen
Pyrrolidines and Piperidines by Ligand-Enabled Aza-Heck Cyclizations and Cascades of <i>N</i>
-(Pentafluorobenzoyloxy)carbamates
作者:Ian R. Hazelden、Rafaela C. Carmona、Thomas Langer、Paul G. Pringle、John F. Bower
DOI:10.1002/anie.201801109
日期:2018.4.23
Ligand‐enabled aza‐Heck cyclizations and cascades of N‐(pentafluorobenzoyloxy)carbamates are described. These studies encompass the first examples of efficient non‐biased 6‐exo aza‐Heck cyclizations. The methodology provides direct and flexible access to carbamate protected pyrrolidines and piperidines.
Pd/Et3B and Pd/Et2Zn systems promote the nucleophilic allylations of 2-aminotetrahydrofuran and 2-aminotetrahydropyran with allylic alcohols to provide omega-hydroxyhomoallylamines in high yields. The transformation is applicable to the allylation of non-protective carbohydrates, such as ribose and deoxyribose. (C) 2010 Elsevier Ltd. All rights reserved.