<i>N</i>,<i>N</i>‘-Ditosylhydrazine: A Convenient Reagent for Facile Synthesis of Diazoacetates
作者:Tatsuya Toma、Jun Shimokawa、Tohru Fukuyama
DOI:10.1021/ol701432k
日期:2007.8.1
A novel entry to the synthesis of diazoacetates is disclosed. A variety of diazoacetates were synthesized from the corresponding bromoacetates by treatment with N,N'-ditosylhydrazine in moderate to high yields. Ease of operation with the stable crystalline reagent as well as a short reaction time offer a useful alternative to the conventional methods.
The intramolecularcyclopropanation of various trans-allylic diazoacetates and alkenyl diazoketones has been achieved with excellent enantioselectivities of up to 98% ee and in quantitative yields by using a water-solubleruthenium(II)/hydroxymethyl(phenyl)oxazoline catalyst in a water/ether biphasic medium. The catalyst could be reused at least five times.
A Convenient Access to γ‐Lactones from
<i>O</i>
‐Allyl‐α‐Bromoesters using a One‐Pot Ionic–Radical–Ionic Sequence
作者:Romain Bénéteau、Jacques Lebreton、Fabrice Dénès
DOI:10.1002/asia.201200212
日期:2012.7
α‐bromo ester precursors with DIBAL‐H and radical cyclization of the resulting O‐aluminum acetals, a preparative in‐situ Oppenauer‐type oxidation of the cyclic O‐aluminum acetal using simple aldehydes or ketones gives access to γ‐lactones in high yields.
Photocatalytic 1,2-oxo-alkylation reaction of styrenes with diazoacetates
作者:Fang Li、Siqi Zhu、Rene M. Koenigs
DOI:10.1039/d2cc02414d
日期:——
reactivity of diazoalkanes can be suppressed and a 1,2 oxo-alkylation reaction can be achieved (32 examples, up to 94% yield) without the formation of cyclopropane by-products via the formation of radical intermediates from ethyldiazoacetate.
Visible Light-Promoted Diazoacetates and Nitriles Generating Nitrilium Ions Trapped by Benzotriazoles and Carboxylic Acids
作者:Keyong Zhu、Mengting Cao、Guanzhen Zhao、Jingjing Zhao、Pan Li
DOI:10.1021/acs.orglett.2c02426
日期:2022.8.12
A visible light-promoted generation of nitriliumions from diazoacetates and nitriles has been developed. The reaction utilized visible light transformation of diazoacetates to the free carbene that could be trapped by nitriles to generate nitriliumions, followed by nucleophilic attack on the benzotriazoles and carboxylic acids. This protocol provides an efficient and practical approach to N-imidoylbenzotriazoles