81878-54-8Relevant articles and documents
Reaction rate differences between organotrifluoroborates and boronic acids in BINOL-catalyzed conjugate addition to enones
Brooks, Bailey,Hiller, Noemi,May, Jeremy A.
supporting information, (2021/09/28)
Enantioselective organocatalysis has been successfully employed in combination with trifluoroborate reagents for novel organic transformations over the last decade. However, no experimental rate studies of these reactions have been reported. Herein we report Hammett plot analysis of the organocatalyzed enantioselective conjugate addition of alkenyl, aryl, and heteroaryl trifluoroborate salts to chalcone derivatives with substitution at both the β-aryl and keto-aryl positions. The rate trend for keto-aryl substitution diverges from that of boronic acid nucleophiles in that the keto-aryl substituent for trifluoroborate salts does not measurably impact reaction rate in a manner consistent with charge stabilization. In addition, variable temperature NMR in combination with quantitative thin-layer chromatography (TLC) analysis suggests that the reaction is impacted by the low solubility of the trifluoroborate salts, so particle size and stirring speed affect reaction rates.
Achieving Enantioselectivity in Difficult Cyclohexa-1,3-diene Diels-Alder Reactions with Sulfur-Stabilized Silicon Cations as Lewis Acid Catalysts
Shaykhutdinova, Polina,Oestreich, Martin
supporting information, p. 7029 - 7033 (2018/11/24)
A novel cationic silicon-sulfur Lewis pair with a chiral H8-binaphthyl backbone is reported. It catalyzes otherwise sluggish Diels-Alder reactions of cyclohexa-1,3-diene and chalcone derivatives in good yields and decent enantioselectivities (up to 81% ee). The enantioinduction is highest with a [1,1′-biphenyl]-4-yl substituent at the carbonyl carbon atom. This moiety can be later converted into a carboxyl group by Baeyer-Villiger oxidation. The same oxidant also epoxidizes the double bond in the cycloadduct, and the epoxide engages in a lactonization with the carboxylic acid. Synthetically interesting hexahydro-3,6-methanobenzofuran-2(3H)-one skeletons are obtained in one pot.
Polyaniline coated on celite, a heterogeneous support for palladium: Applications in catalytic Suzuki and one-pot Suzuki-aldol reactions
Patel, Heta A.,Patel, Arun L.,Bedekar, Ashutosh V.
, p. 8935 - 8945 (2016/10/13)
Particles of celite were coated with polyaniline, characterized and used as a support for heterogenization of palladium metal ions. The prepared heterogeneous palladium catalysts were screened for Suzuki-Miyaura and one-pot Suzuki-aldol reactions with high conversions. The process of heterogenization on celite reduces the PANI consumption ten-fold when anchoring palladium ions onto the support. The recyclable catalyst was also used for the sunlight mediated Suzuki-Miyaura reaction with good conversion.
