Rh(III)-Catalyzed Oxidative Coupling of Benzoic Acids with Geminal-Substituted Vinyl Acetates: Synthesis of 3-Substituted Isocoumarins

Abstract

The Rh(III)-catalyzed C-H activation initiated cyclization of benzoic acids with electron-rich geminal-substituted vinyl acetates was described. The reaction was employed to prepare a range of 3-aryl and 3-alkyl substituted isocoumarins selectively.

1‐Phenyl‐1,2‐benziodoxol‐3‐(1H)‐one as Synthon for Phthalide Synthesis through Pd‐Free, Base‐Free, Sonogashira‐Type Coupling Cyclization Reaction

“…3‐Methyl‐1 H ‐isochromen‐1‐one (7i): 1‐Phenyl‐1,2‐benziodoxol‐3‐(1 H )‐one ( 1 ; 520 mg, 1.6 mmol), and trimethyl(prop‐1‐yn‐1‐yl)silane ( 5i ; 90 mg, 0.8 mmol), Cu(NCCH 3 ) 4 PF 6 (0.16 mmol) afforded title compound 7i as a white solid. Yield 25 mg (0.15 mmol, 17 %).…”

Synthetic Methods of Isocoumarins and Phosphaisocoumarins through CH Activation

“…Reaction of 1‐alkyl vinyl acetates with benzoic acids produced 3‐alkyl‐substituted isocoumarins as a major product. This method afforded an efficient pathway to a wide range of isocoumarin derivatives (f) . Isocoumarin derivatives were prepared through Rh(III)‐catalyzed CH activation/esterification of benzoic acids with cyclic 2‐diazo‐1,3‐diketones under mild conditions (g) .…”

Rh‐Catalyzed Synthesis of Oxygen‐Containing Heterocycles

“…The same group also developed the rhodium-catalyzed coupling of acrylic acids with alkynes to provide corresponding α-pyrone via vinylic C-H bond cleavage (Scheme 6.24c) [5c]. In 2015, Wen and coworkers described a Rh(III)-catalyzed synthesis of 3-substituted isocoumarins from benzoic acids with geminal-substituted vinyl acetates (Scheme 6.24d) [39]. In 2013, the synthesis of phosphaisocoumarins is achieved by Miura and coworkers via Rh(III)-catalyzed oxidative annulation of phenylphosphonic acids with alkynes (Scheme 6.25a) [40].…”