A straightforward synthetic method for the preparation of isocoumarins and 3-benzylidenephthalides via C-H olefination and oxidative coupling of readily available benzoic acids and vinylarenes was developed. The directing effect of the substituents on the benzoic acid allows for the synthesis of both types of lactone in pure form.

The preparation of a series of ligand precursors that feature imidazo[1,2‐a]pyridine and amido functional groups is reported. The reactions between the new ligand precursors, pyridine, and palladium acetate in DMF afforded monodentate PdII abnormal (mesoionic) carbene complexes. An isomeric PdII normal carbene complex with a formally identical steric environment to that of the abnormal carbene counterpart was also prepared. The isomeric pairs were characterized by X‐ray structural studies. Under different complexation conditions, in which PdCl2 was employed as metal precursor, a zwitterionic CC‐type palladacycle formed by the C–H activation at the ortho‐N‐phenyl and methylene carbon atoms was obtained. The use of a similar ligand precursor with an NH instead of an NMe group produced a zwitterionic palladalactam complex. In contrast to the previous work in the literature, owing to the rigidity of the fused heterocyclic ring, the palladalactam complex did not undergo intramolecular proton transfer through the coordinated N atom. Overall, we demonstrated that proper modification of the structures of ligand precursors and complexation conditions allowed us to obtain a full range of intriguing PdII complexes including normal and abnormal carbene complexes, and zwitterionic palladalactam and CC‐type palladacycles by means of A–H bond (A = N, C) activations.

A series of cobalt(II) phenoxy‐imine complexes (CoII(FI)2) have been synthesized to mediate the radical polymerization of vinyl acetate (VAc) and methyl acrylate (MA) to evaluate the influence of chelating atoms and configuration to the control of polymerization. The VAc polymerizations showed the properties of controlled/living radical polymerization (C/LRP) with complexes 1a and 3a, but the catalytic chain transfer (CCT) behaviors with complexes 2a, 1b, 2b, and 3b. The control of VAc polymerization mediated by complex 1a could be improved by decreasing the reaction temperature to approach the molecular weights that not only linearly increased with conversions but also matched the theoretical values and relatively narrow molecular weight distributions. The catalytic chain transfer polymerizations (CCTP) mediated by complexes 2a, 1b, 2b, and 3b were characterized by Mayo plots and the polymer chain end double bonds were observed by 1H NMR spectra. The tendency toward C/LRP or CCTP in VAc polymerization mediated by CoII(FI)2 could be determined by the ligand structure. Cobalt complex coordinated by the ligand with more steric hindered and less electron‐donating substituents favored the controlled/living radical polymerization. In contrast, the efficiency of CCT process could be enhanced by less steric hindered, more electron‐donating ligands. The controlled/living radical polymerization of MA, however, could not be achieved by the mediation of these cobalt(II) phenoxy‐imine complexes. Associated with the results of polymerization mediated by other cobalt complexes, this study implied that the configuration and spin state of cobalt complexes were more critical than the chelating atoms to the control behavior of radical polymerization. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 101–113

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One-Step Synthesis of Isocoumarins and 3-Benzylidenephthalides via LigandlessPd-Catalyzed Oxidative Coupling of Benzoic Acids and Vinylarenes. -Different benzoic acids containing electron-drawing groups can be converted into the corresponding coumarines or phtalides via the simple title reaction. 2-Nitro-benzoic acid (X) undergoes a decarboxylative Heck-coupling reaction under the same reaction conditions. Moreover, the synthesis of the biologically active thunberginol F (XV) can be realized with this method. -(NANDI, D.; GHOSH, D.; CHEN, S.-J.; KUO, B.-C.; WANG, N. M.; LEE*, H. M.; J. Org. Chem. 78 (2013) 7, 3445-3451, http://dx.doi.org/10.1021/jo400174w ; Dep. Chem., Natl. Changhua Univ. Educ., Changhua 50058, Taiwan; Eng.) -M. Zastrow 33-159