Phosphorus‐Directed Rhodium‐Catalyzed C−H Arylation of 1‐Pyrenylphosphines Selective at the K‐Region

Abstract

CÀ H arylation of 1-pyrenylphosphine derivatives catalyzed by rhodium and directed by a diphenylphosphino group is selectively achieved at the K-region, i. e. 4-, 5-, 9-, or 10-position of the pyrene moiety. This peri CÀ H activation/arylation of pyrenes using (hetero)aryl bromide coupling partners tolerates both electron-donating and electron-withdrawing groups on the arene, and provides isolated yields of products between 25% to 90%, including from bulky polyaromatic bromoarene substrates. We achieved investigations directed at the formation and reactivity of pertinent intermediate species in this CÀ H arylation reaction. The P-ligand coordination at rhodium was established using 31 P NMR and XRD analysis, and we isolated five-membered rhodacycles as intermediates to the directed CÀ H functionalization. The data obtained overall supported the occurrence of a cationic rhodium catalytic process. We further described the access to a large class of pyrenylphosphine ligands and their selenated derivatives. Phosphine selenation allows to rapidly estimate from 1 J P = Se values the basic character of the ligand in the perspective of their use for coordination. Accordingly, linear P-coordinated Au(I) gold complexes were isolated, in addition to the variously coordinated Rh(III) complexes. The present methodology significantly extends the scope of polyaromatics that are functionalizable at the K-Region by direct CÀ H activation, beyond smaller-sized naphtalenes and aminopyrenes.

Palladium-catalysed C–H arylation of benzophospholes with aryl halides

“…Additionally notable is the high C2–H regioselectivity in spite of the possibility of phosphole P O-directed C–H functionalisation of the phenyl group on phosphorus. 16 The P O-directed second arylation of the C2–H arylation product was actually detected in ca. 10% yield in the prolonged reaction periods with the conventional oil bath heating (data not shown), but the formation of such a diarylation byproduct could be avoided under the microwave irradiation.…”

Aryl Triflates in Phosphorus-Directed Rhodium(III)-Catalyzed C–H Activation

“…The steric congestion from polyaromatic triflates did not hampered the reaction, and in the presence of 2naphthyl, 1-naphthyl or 9-phenanthrenyl groups the corresponding coupling products 13 (89%), 14 (32%) and 15 (76%) were obtained (Figure 2). Our protocol was successfully extended to other PAH dimonophosphines (17)(18)(19), Figure 3). 1-Naphthyl diphenylphosphine gave 88%, 93% and 55% isolated yield for 20, 21 and 22, respectively, in the presence of electronwithdrawing groups (with acetyl, nitrile and trifluoromethyl groups, respectively), and 87%, 55% and 51% for 23, 24 and 25 respectively, in the presence of electron-rich triflate as coupling…”

Transmission of spin-polarization by π-orbitals: an approach to assessing its effect on NMR spin–spin coupling and EPR hyperfine structure

“…Our motivation for addressing the topic of p-TSP is as follows: (a) though the p-TSP effect on the EPR hyperfine coupling constants (HFCCs) was discussed long ago, 4,6 its detailed analysis has received much less attention than the influence of p-TSP on NMR spin-spin coupling; (b) deeper insight into p-TSP can be gained by the methods of visualization of pathways of NMR spin-spin couplings and EPR hyperfine couplings that are now available; 14 (c) to the best of our knowledge, a consistent explanation for the sign alternation of the p-TSP effect along the bonds on SSCCs and HFCCs is still lacking; (d) deeper understanding of p-TSP may be beneficial for further analyzing spin-spin transmission pathways in transition metal complexes that include aromatic moieties in their ancillary ligands (phenyl, naphthyl, etc.) 15 or that possess benzene and olefins as ligands themselves (metallocenes, etc.). 16 The aim of this work is to present an approach that allows one to switch the p-TSP effect off and on easily, and which is applicable to the analysis of molecular properties that depend on the effects of spin-polarization (SSCC, HFCC).…”