No abstract

A thermoresponsive polymeric Pd-complex was synthesized, enabling highly efficient cross-couplings and continuous catalyst-recycling flow reactions with ultralow Pd usages.

A continuous-flow chemistry facilitated protocol that allows efficient access to a novel aggregation-induced emission (AIE) luminogen 1,1-diphenylvinylsulfides utilizing thiols under metal-free and mild conditions.

A poly(ethylene glycol) (PEG) linked ortho-MeOphenyldicyclohexylphosphine (MeO-WePhos) ligand has been synthesized to promote Pd-catalyzed carbon-carbon bond formation by cross-couplings including Sonogashira, Heck, Hiyama and Stille reactions, providing corresponding (hetero)aryl substituted alkynes, alkenes and bi(hetero)aryls in good to excellent isolated yields with low Pd loadings. Facilitated by the lower critical solution temperature behaviour of the polymeric monophosphine ligand, the metalcomplex could rapidly shuttle between organic and water phases as regulated by temperature, enabling highly efficient catalyst recycling via a simple phase separation. The chemical structure of ligand was determined by matrixassisted laser desorption/ionization-time of flight mass spectrometry, nuclear magnetic resonance spectrometry and size-exclusion chromatography measurements. Notably, as demonstrated by the inductively coupled plasma-atomic emission spectrometry measurement, 98% Pd was kept in the water phase after 6 cycles of catalyst recycling experiments. Given the profound impact of transition-metalcatalyzed covalent bond formation and the increasing demand of sustainable chemistry, this work provides an alternative method to conduct cross-couplings with a polymeric shuttling catalyst. Scheme 5. Hiyama and Stille reaction with MeO-WePhos 5000 4 a. Conditions: 23 (0.5 mmol), 24 (0.6 mmol), K 2 CO 3 (1.0 mmol), water (0.8 mL), toluene (0.2 mL), 90°C, 6 h. Isolated yields are based on aryl bromides 23.