Efficient stereochemical communication in phosphine-amine palladium-complexes: Exploration of N-substituent effects in coordination chemistry and catalysis

Synthesis of zwitterionic phosphapalladacycles: unusual reactivity pattern of six-membered P,N-chelates

“…Strikingly, the X-ray structure revealed a six-membered palladium chelate with P,C σ coordination (Figure ). In contrast to compounds 1a – d , pentane-2,4-diyl based P,N ligands with a secondary amino functionality form stable six-membered P,N chelates or 12-membered binuclear cycles with [Pd­(COD)­Cl 2 ], as was reported earlier. , …”

“…Instead, two new diastereotopic methylene signals were detected at 3.46 and 2.78 ppm, respectively, indicating the presence of Pd–CH 2 protons. The 31 P signal of 2a at 42.44 ppm is out of the range (21.6–27.6 ppm) found for six-membered [Pd­(P,N)­Cl 2 ] chelates with a pentane-2,4-diyl backbone . Furthermore, on comparison of the 13 C­{ 1 H} and 13 C DEPT NMR spectra a quaternary carbon signal (CN) appeared at 184.81 ppm with a coupling constant of J (P,C) = 5.6 Hz.…”

“…Five-membered P,N chelates with secondary and tertiary amine functionalities as well as six-membered P,N chelates with secondary amine functionalities , are more stable than the six-membered P,N chelates formed by ligands 1a – d bearing a tertiary amine moiety. This indicates that the formation of reactive free coordination sites is hampered in the former cases.…”

Enantiodivergent Hydrogenation of Exocyclic α,β‐Unsaturated Lactams Enabled by Switching the N‐Chirality of Iridium Catalyst

“…In terms of our continuous interest in developing new chiral ligands and catalysts, we wondered whether the configuration of the N‐stereocenter of a metal complex catalyst could be switchable and selectively formed in coordination process (Scheme 1d), which may benefit the enantiodivergent catalysis. In this work, we report the design, synthesis, and application of a class of simple P,N‐ligands [4w–ac] with flexible N‐based stereogenic centers and their derived iridium complexes with fixed N‐based stereogenic centers. These ligands could coordinate with [Ir(COD)Cl] 2 to selectively yield a pair of diastereoisomeric iridium complexes with opposite configurations of the N‐stereocenter, which are kinetically favored products or thermodynamically stable products of the coordination process (Scheme 1e).…”

Preparation and Application of Amino Phosphine Ligands Bearing Spiro[indane-1,2′-pyrrolidine] Backbone

“…P,N-bidentate compounds are well known as chiral ligands. Although various chiral P,N-bidentate ligands have been reported, successful reports on P,N sp 3 -bidentae ligands are still limited. The heterobidentate character as well as the underdevelopment state of P,N sp 3 -bidentate ligands arouses our interest.…”