Progress in (Thio)urea? and Squaramide?Based Brønsted Base Catalysts with Multiple H?Bond Donors
نویسندگان
چکیده
منابع مشابه
Enhanced Efficiency of Thiourea Catalysts by External Brønsted Acids in the Friedel–Crafts Alkylation of Indoles
A novel study of external Brønsted acid-assisted thiourea catalysts in the asymmetric FriedelCrafts alkylation of indoles with nitroalkenes is reported. The final 3-substituted indoles derivatives are synthesized with better results by cooperative effect between chiral thiourea and a Brønsted acid additive (1a·HA), than those obtained with sole thiourea catalyst 1a. The effect of diverse catal...
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For the first time, a catalytic asymmetric Henry reaction of 1H-pyrrole-2,3-diones was achieved with a chiral bifunctional amine-thiourea as a catalyst possessing multiple hydrogen-bond donors. With this developed method, a range of 3-hydroxy-3-nitromethyl-1H-pyrrol-2(3H)-ones bearing quaternary stereocenters were obtained in acceptable yield (up to 75%) and enantioselectivity (up to 73% ee).
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We recently demonstrated that chiral cyclopropenimines are viable Brønsted base catalysts in enantioselective Michael and Mannich reactions. Herein, we describe a series of structure–activity relationship studies that provide an enhanced understanding of the effectiveness of certain cyclopropenimines as enantioselective Brønsted base catalysts. These studies underscore the crucial importance of...
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چکیده ندارد.
1 Lewis Acid – Brønsted Base Catalysis
From the synthetic point of view, organic synthesis via catalytic processes offers many benefits. Catalysis frequently obviates the excessive use of the activating reagents and associated tedious purification processes, thereby offering more environmentally benign synthetic processes. Furthermore, the specific activation mode of a catalyst allows for highly chemoselective transformations that a...
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ژورنال
عنوان ژورنال: European Journal of Organic Chemistry
سال: 2023
ISSN: ['1434-193X', '1099-0690']
DOI: https://doi.org/10.1002/ejoc.202201254