Stereoselective Palladium-Catalyzed Functionalization of Homoallylic Alcohols: A Convenient Synthesis of Di- and Trisubstituted Isoxazolidines and β-Amino-δ-Hydroxy Esters
作者:Andrei V. Malkov、Maciej Barłóg、Lucie Miller-Potucká、Mikhail A. Kabeshov、Louis J. Farrugia、Pavel Kočovský
DOI:10.1002/chem.201102716
日期:2012.5.29
Enantiopure, Boc‐protected alkoxyamines 12 and 13, derived from the readily available homoallylicalcohols 4 via a reaction that involves either inversion or retention of configuration, undergo a diastereoselective Pd‐catalyzed ring‐closing carbonylative amidation to produce isoxazolidines 16/17 (≤50:1 diastereoisomer ratio (d.r.)) that can be readily converted into the N‐Boc‐protected esters of β‐amino‐δ‐hydroxy
Stereoselective Electrophilic
Cyclisation of <i>O</i>-Homoallyl Hydroxylamine Derivatives
作者:Armido Studer、Birgit Janza
DOI:10.1055/s-2002-34385
日期:——
isoxazolidines with moderate cis-selectivity (up to 7: 1). Electrophilic cyclisation of N-acylated O-homoallyl hydroxylamines provides isoxazolines or isoxazolidines depending on the reaction conditions (reagents). The t-BuOCl-mediated cyclisation affords isoxazolines via an oxidative cyclisation, whereas the NIS-induced reaction provides the 5-exo-cyclisation product with high stereoselectivity (cis:trans =
Iminium ions generated from isoxazolidines and tetrahydro-1,2-oxazines undergo allylation under Sakurai conditions. Allylated isoxazolidines are formed predominantly as the trans isomer, while oxazines are formed exclusively as the cis isomer.
Synthesis of N,O-Heterocycles by Intramolecular Conjugate Addition of a Hydroxylamine
作者:Roderick Bates、Robert Snell、SusAnn Winbush
DOI:10.1055/s-2008-1072650
日期:——
Isoxazolidines and tetrahydro-1,2-oxazines were produced by a tandem deprotection-intramolecular Michael addition of hydroxylamines. For tetrahydrooxazine formation, high stereoselectivity was observed, even when a quaternary centre was formed.
Stereoselective synthesis of the isoxazolidine ring <i>via</i> manganese(<scp>iii</scp>)-catalysed aminoperoxidation of unactivated alkenes using molecular oxygen in air under ambient conditions
In this study, we developed a route for the tris(mono-ferrocene-functionalised β-diketonato) manganese(III)-complex catalysed diastereoselective oxygenative aminoperoxidation of unactivated alkenes using molecular oxygen in air. In the reaction, ethanol is used as a solvent, and it proceeds at room temperature under open air. Due to its wide range of substrate scope, functional tolerance, simple operation
在这项研究中,我们开发了一种利用空气中的分子氧对未活化烯烃进行三(单二茂铁-官能化 β-二酮)锰 ( III ) 络合物催化的非对映选择性含氧氨基过氧化反应的路线。该反应以乙醇为溶剂,在室温下露天进行。由于其广泛的底物范围、功能耐受性、操作简单以及温和环保的条件,该反应是一种很有前景的合成方法,可用于合成有价值的异恶唑烷环,不仅是天然产物中的特权结构,而且是 1,3- 的多功能合成子。氨基醇。