Accelerated Discovery in Photocatalysis by a Combined Screening Approach Involving MS Tags
作者:Michael Teders、Sabrina Bernard、Karin Gottschalk、J. Luca Schwarz、Eric A. Standley、Elodie Decuypere、Constantin G. Daniliuc、Davide Audisio、Frédéric Taran、Frank Glorius
DOI:10.1021/acs.orglett.9b03936
日期:2019.12.6
on the development of an MS tag screening strategy that accelerates the discovery of photocatalytic reactions. By efficiently combining mechanism- and reaction-based screening dimensions, the respective advantages of each strategy were retained, whereas the drawbacks inherent to each screeningapproach could be eliminated. Applying this approach led to the discovery of a mild photosensitized decarboxylative
method for constructing 1,4-pyrazoles from arylglycines was developed using the copper-catalyzed sydnone–alkyne cycloaddition reaction. The procedure offers a straightforward and general route to the pyrazole heterocycle through a three-step one-pot procedure.
reactivity towards both copper‐catalyzed and strain‐promoted cycloaddition reactions with alkynes. Synthetic access to these new mesoionic compounds was granted by electrophilic fluorination of σ‐sydnone PdII precursors in the presence of Selectfluor. Their reactions with terminal and cyclic alkynes were found to proceed very rapidly and selectively, affording 5‐fluoro‐1,4‐pyrazoles with bimolecular
我们报告了4-氟丁酮的合成和反应性,这是一类独特的中离子偶极子,对炔烃的铜催化和应变促进的环加成反应均显示出出色的反应性。在Selectfluor的存在下,通过σ-sydnonePd II前体的亲电氟化反应,可以合成这些新的中离子化合物。发现它们与末端和环状炔烃的反应非常迅速且选择性地进行,从而提供双分子速率常数高达10 4 m -1 s -1的5-氟-1,4-吡唑,超过了文献中有关环炔烃的文献记载。进行了动力学研究以阐明反应的机理,并成功地用[ 18 F] Selectfluor进行了放射性标记,进一步突出了4-氟丁酮的价值。
Copper(I)-Catalyzed Cycloaddition of 4-Bromosydnones and Alkynes for the Regioselective Synthesis of 1,4,5-Trisubstituted Pyrazoles
Copper-catalyzed cycloaddition of alkynes with 4-bromosydnones provides a convenient, mild, and regioselective method for the synthesis of a wide range of bromopyrazoles. The broad functional group tolerance of the cycloaddition reaction and further palladium-catalyzed cross-coupling reactions allowed the preparation of polyfunctionalized 1,4,5-pyrazoles that are otherwise difficult to obtain by conventional
of 4-trifluoromethyl pyrazoles have been prepared via the copper-catalyzed cycloaddition of 2-bromo-3,3,3-trifluoropropene with a variety of N-arylsydnone derivatives under mild conditions. This new protocol under optimized reaction conditions [Cu(OTf)2/phen, DBU, CH3CN, 35 °C] afforded 4-trifluoromethyl pyrazoles in moderate to excellent yields with excellent regioselectivity.