A tricyclic phosphine has been generated that has a rigid molecular backbone with the P atoms exclusively bound to C(sp ) atoms as well as a very large Tolman angle and buried volume. It is an interesting new ligand in coordination chemistry (Au, Pd complexes) and shows unusual insertion reactions into its endocyclic P-C bonds facilitated by its inherent molecular strain.
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http://dx.doi.org/10.1002/anie.201711373 | DOI Listing |
J Org Chem
September 2024
University of Rostock, Institute of Chemistry, Albert-Einstein-Str. 3a, Rostock 18059, Germany.
Dihydroazepino[1,2-]indole diones are tricyclic -acyl-2-alkylidene-3-oxindole enones that readily engage in tertiary phosphine-catalyzed intermolecular coupling reactions with acceptor-substituted alkenes. In these reactions, the tricyclic α-substituted enones undergo an α-alkylation with concomitant formation of a quaternary stereocenter, as well as the installation of a new double bond within the seven-membered azepane ring. The organocatalytic reaction constitutes a special case of the crossed intermolecular Rauhut-Currier reaction as the presence of the α-substituent in the enones prohibits the formation of an α,β-unsaturated product, but instead, skipped β,γ-unsaturated enones are obtained.
View Article and Find Full Text PDFJ Org Chem
December 2023
Anorganische und Allgemeine Chemie, Department Chemie und Pharmazie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany.
Inversion barriers Δ for planar chiral phosphine-alkene and sulfonamide-alkene hybrid ligands based on phenyl-dibenz[]azepine have been determined by density-functional theory calculations. Analysis of the structural and electronic characteristics of the minima and transition states explains the magnitudes of Δ and the geometrical changes during the inversion process. The steric repulsion caused by bulky substituents attached to the azepine nitrogen atom has a pronounced effect on the Δ value, explaining, inter alia, the stereochemical stability of the P- and S-alkene ligands when compared to the fluxional parent compound where X = H.
View Article and Find Full Text PDFInorg Chem
February 2023
State Key Laboratory of Elemento-Organic Chemistry and College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China.
A new strategy for the introduction of a second type of Si atom to silicon cubanes has been developed starting from the tricyclic hexasilane dianion [ArSi] (Ar = 2,4,6-MeCH). Treatment of the dianion with Ar'SiCl, followed by KC, gave new types of octasilacubanes ArAr'Si [Ar' = 2,4,6-PrCH (), 2-PhPCH ()] in high yields. Remarkably, treatment of cubane bearing with two phosphine groups with 2 equiv of CuCl in CHCl yielded the bis(silyl)copper complex via the selective oxidative addition of the newly formed Si-Si bond to Cu ion.
View Article and Find Full Text PDFChem Sci
November 2020
Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong Shatin New Territories Hong Kong China
Intramolecular vicinal Frustrated Lewis Pairs (FLPs) have played a significant role in the activation of small molecules, and their stabilities and reactivities are found to strongly depend on the nature of the bridging units. This work reports a new carborane based FLP, 1-PPh-2-BPh-1,2-CBH (), which reacts with an equimolar amount of -RNCHC[triple bond, length as m-dash]CH (R = Me, Et, Ph) at room temperature to give C[triple bond, length as m-dash]C triple bond addition products 1,2-[PPhC(RNCH)[double bond, length as m-dash]CHBPh]-1,2-CBH () in high yields. Compounds react further with two equiv.
View Article and Find Full Text PDFThe redox behaviour of sterically constrained tricyclic phosphine was investigated by spectroelectrochemistry. The data suggested a highly negative reduction potential with the reversible formation of a dianionic species. Accordingly, reacted with two equivalents of Li/naphthalene by reductive cleavage of a P-C bond of one of the PC heterocycles.
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