Synthesis of vitamin D analogues with a 2-hydroxy-3-deoxy ring A
摘要:
We present a short, practical synthesis of new C2-hydroxylated vitamin D analogues. The enantioselective synthesis of a phosphine oxide precursor involves, as key step, a catalytic asymmetric allylation. (C) 2000 Elsevier Science Ltd. All rights reserved.
acceleration effect of an allylic hydroxy group on ring-closing enyne metathesis has been found. Ring-closing enyne metathesis of terminalalkynes possessing an allylic hydroxy group proceeded smoothly without the ethylene atmosphere generally necessary to promote the reaction. The synthesis of (+)-isofagomine with the aid of this efficient reaction has been demonstrated. Mechanistic studies of the acceleration
strategic syntheses and bioorthogonal studies is always problematic. The chiral columnhigh-performanceliquidchromatography (HPLC) method in general could not be directly used to resolve such substrates, since the differentiation of the alkyne segment with the other alkane/alkene segment is not significant in the stationary phase, and the alkyne group is not a good UV chromophore. Usually, a pre-column
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。
Enantioselective (8+3) Cycloadditions by Activation of Donor–Acceptor Cyclopropanes Employing Chiral Brønsted Base Catalysis
作者:David A. McLeod、Mathias Kirk Thøgersen、Casper Larsen Barløse、Mette Louise Skipper、Erlaitz Basabe Obregón、Karl Anker Jørgensen
DOI:10.1002/anie.202206096
日期:2022.7.18
A non-covalent organocatalytic enantioselective (8+3) cycloaddition of donor–acceptorcyclopropanes and heptafulvenoids is reported. The reaction design employs an anionic cyclopropane activation strategy by employing a bifunctional optically-active Brønsted base. The reaction pathway and mechanism of stereochemical control was investigated by DFT calculations.