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J Org Chem
September 2021
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Pyridazines are important scaffolds for medicinal chemistry or crop protection agents, yet the selective preparation of 3-bromo-pyridazines with high regiocontrol remains difficult. We achieved the Lewis acid-mediated inverse electron demand Diels-Alder reaction between 3-monosubstituted -tetrazine and silyl enol ethers and obtained functionalized pyridazines. In the case of 1-monosubstituted silyl enol ethers, exclusive regioselectivity was observed.
View Article and Find Full Text PDFOrg Lett
September 2020
Institute for Advanced Study, Chengdu University, Chengdu 610106, China.
The first catalytic enantioselective dearomatization/rearomatization of 2-nitroindoles triggered by the Michael addition of 3-monosubstituted oxindoles was established. A wide range of 3-indolyl-3'-alkyloxindoles (up to 99% yield, 97% ee) and 3-indolyl-3'-aryloxindoles (up to 95% yield, 99% ee) were obtained by using an organocatalyst. This method provides an unprecedented strategy to access structurally diverse 3,3'-disubstituted oxindoles bearing a sterically congested triaryl-containing all-carbon quaternary stereocenter.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2020
Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
Since tetrazines are important tools to the field of bioorthogonal chemistry, there is a need for new approaches to synthesize unsymmetrical and 3-monosubstituted tetrazines. Described here is a general, one-pot method for converting (3-methyloxetan-3-yl)methyl carboxylic esters into 3-thiomethyltetrazines. These versatile intermediates were applied to the synthesis of unsymmetrical tetrazines through Pd-catalyzed cross-coupling and in the first catalytic thioether reduction to access monosubstituted tetrazines.
View Article and Find Full Text PDFWe report the synthesis and first characterisation of the novel chemical probe 3-bromotetrazine and establish its reactivity towards nucleophiles. This led to the synthesis of several novel classes of 3-monosubstituted -tetrazines. A remarkable functional group selectivity is observed and is utilised to site-selectively functionalise different complex molecules.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
September 2018
PPSM- CNRS- ENS Paris-Saclay, 61 Avenue Président Wilson, 94235, Cachan, France.
A facile, efficient and metal-free synthetic approach to 3-monosubstituted unsymmetrical 1,2,4,5-tetrazines is presented. Dichloromethane (DCM) is for the first time recognized as a novel reagent in the synthetic chemistry of tetrazines. Using this novel approach 11 3-aryl/alkyl 1,2,4,5-tetrazines were prepared in excellent yields (up to 75 %).
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