Synthesis of isocoumarins via thallation-olefination of benzoic acids

Palladium(II)‐Catalyzed Enantioselective C−H Alkenylation of Ferrocenecarboxylic Acid

“…Increasing the loading of Pd(OAc) 2 to 1 equiv., 80% mixed products ( 4A and 5A with ratio of 16.9:1) were provided using benzoic acid as the substrate under N 2 (eq 6). Under oxygen conditions, 5A was afforded as the main product (eq 5), because 2‐alkenyl benzoic acid 4A is easily converted to the cyclized product 5A . These results obtained indicated that both O 2 and ferrocene moiety were crucial for such a transformation, and suggest that ferrocenium might be formed in situ by O 2 and serve as an terminal oxidant to regenerate Pd(II) species from reduced Pd(0) for the next catalytic process.…”

Recent Progress in the Chemistry of Allenes

“…These heteroannulations employing oxygen-substituted precursors show partly different criteria in terms of ring size and selectivity in comparison with the carboannulations and heteroannulations using the above nitrogen compounds. However, unlike the cyclizations involving amine and malonate functionality, the reactions of hydroxy terms of regioselectivity in the palladium(II)-catalyzed reactions of ortho-thallated benzoic acid 209 and various allenes 137 were obtained earlier (Scheme 38) [117]. It should be noted that the enantioselective heteroannulations using oxygen-functionalized aryl and vinylic iodides, but compared to the nitrogenannulated products, the oxygenannulated compounds showed lower enantioselectivities and yields [115,116].…”

Heterocycle Formation via Palladium-Catalyzed C-H Functionalization

“…73 An attractive approach for heterocycle formation would thus be to merge this chemistry with a subsequent reaction in which the olefinated product would undergo intramolecular 1,4-conjugate addition or Wacker-type oxidative cyclization. 74 For instance, Miura and coworkers developed such a sequence to generate phenanthridine derivative 133 (Scheme 34). 75 The acidity of the sulfonamide N–H bond is quite crucial, since other amides proved to be ineffective.…”