3619-02-1Relevant articles and documents
Microwave-assisted cleavage of cysteine perfluoroaryl thioethers
Bednar, Taylor N.,Resnikoff, Alissa R.,Gavenonis, Jason
, p. 841 - 845 (2020)
The cysteine- perfluoroarene SNAr reaction allows for the sequence-specific attachment of dyes and affinity tags to peptides and proteins. However, while many methods exist for the desulfuration of native and functionalized cysteine residues, there are no reports of their application to perfluoroarylated cysteines. Herein we report both the hydrogenolysis of a perfluoroarylated cysteine to alanine and elimination to dehydroalanine, reactions that are both accelerated by microwave irradiation.
2-(1S)-Camphanoyloxy-2′-phosphanylbiphenyl Ligands – Synthesis, Structure, and Preliminary Tests in Transition-Metal Catalysis
Wawrzyniak, Piotr,Kindermann, Markus K.,Thede, Gabriele,Thede, Richard,Jones, Peter G.,Enthaler, Stephan,Junge, Kathrin,Beller, Matthias,Heinicke, Joachim W.
supporting information, p. 2762 - 2773 (2017/06/06)
Diastereoisomer separation of the (1S)-camphanic acid 2-isopropylphenylphosphanyl-phenyl ester 1 exemplifies the potential of (1S)-camphanoyl chloride for enantiomer separation of hydroxyl-functional asymmetric phosphanes. Esterification of lithium 2′-phosphanylbiphenyl-2-olates, generated from the respective 2-OH or 2-OSiMe3 precursors 2aOH and 2b–fSi, furnished the 2-(1S)-camphanoyloxy-biphenylphosphanes 3a–c as 1:1 mixtures of diastereomers with low barriers for interconversion by rotation around the C–C axis (ΔG# = 70–73 kJ mol–1 for 3a and 3c by 31P VT NMR spectroscopy). The P-asymmetric compounds 3d–f form 1:1 mixtures of stereoisomers. There is a tendency to cocrystallization of two preferred diastereoisomers, as shown by the crystal structure analyses of 3dD and 3fD, and in solution, there is a tendency toward partial isomerization to the sterically less-favored atropisomers. The [RhCl(cod)(3dD)] complex 4dD, however, seems stable in solution. Excess 2dLi reacted with (1S)-camphanoyl chloride preferentially to form the (SP,Rax,1S) isomer, which was separated by crystallization as enantiopure 3dE, characterized by single-crystal XRD. Preliminary screening tests of this ligand in Rh-catalyzed asymmetric hydrogenations of N-(1-phenylvinyl)acetamide allowed high conversion and up to 59 % ee. Hydrosilylation of acetophenone proceeded with 78 % conversion and 48 % ee; Suzuki–Miyaura couplings of 1-bromo-2-naphthol with PhB(OH)2, in the presence of 3b/[Pd(OAc)2], gave yields up to 98 %.
Assisted Tandem Catalysis: Metathesis Followed by Asymmetric Hydrogenation from a Single Ruthenium Source
Renom-Carrasco, Marc,Gajewski, Piotr,Pignataro, Luca,Devries, Johannes G.,Piarulli, Umberto,Gennari, Cesare,Lefort, Laurent
supporting information, p. 2223 - 2228 (2015/07/27)
Here we report the first example of a tandem metathesis-asymmetric hydrogenation protocol where the prochiral olefin generated by metathesis is hydrogenated with high enantioselectivity by an in situ formed chiral ruthenium catalyst. We show that either the ruthenium metathesis catalysts or the ruthenium species formed during the metathesis reaction can be converted into an efficient asymmetric hydrogenation catalyst upon addition of a chiral ligand and an alcohol. The performance in asymmetric hydrogenation appears to be very dependent on the solvent, the chiral ligand, and the prochiral substrate.
