Regioselective synthesis of isocoumarins by ruthenium-catalyzed aerobic oxidative cyclization of aromatic acids with alkynes

Abstract

The highly regioselective aerobic oxidative cyclization of aromatic, heteroaromatic and alkenyl acids with alkynes in the presence of catalytic amounts of [{RuCl(2)(p-cymene)}(2)], AgSbF(6) and Cu(OAc)(2)·H(2)O providing isocoumarin derivatives was investigated.

Effect of Cp‐Ligand Methylation on Rhodium(III)‐Catalyzed Annulations of Aromatic Carboxylic Acids with Alkynes: Synthesis of Isocoumarins and PAHs for Organic Light‐Emitting Devices

“…3,4‐Diphenyl‐1H‐benzo[h]isochromen‐1‐one (1 h) : colorless solid; SiO 2 , petroleum ether/dichloromethane (2 : 1); 1 H NMR (CDCl 3 ): δ =7.01–7.58 (m, 11H), 7.65 (t, 1H, J =7.6 Hz), 7.81 (t, 1H, J =7.6 Hz), 7.89 (d, 1H, J =8.0 Hz), 8.01 (d, 1H, J =8.8 Hz), 9.89 (d, 1H, J =8.4 Hz) ppm (cf …”

Ruthenium(II)‐Catalyzed Synthesis of Pyrrole‐ and Indole‐Fused Isocoumarins by C−H Bond Activation in DMF and Water

“…Among several synthetic methods developed in recent years, transition‐metal‐catalyzed syntheses of isocoumarins are the most attractive and environmentally benign . Recently, catalyst derivatives of Cu, Pd, Ru,, and Rh have been employed for the synthesis of isocoumarin derivatives through annulation reactions involving initial functionalization of arene sp 2 C−H bonds. Notably, regioselective functionalization promoted by metal‐catalyzed sp 2 C−H bond activation offers an efficient route for fast access to various functional molecules .…”

“…Recently, ruthenium(II)‐catalyzed annulations involving C−H/N−H and C−H/O−H bond cleavage leading to isocoumarins have been reported by several groups ,. Especially, Jeganmohan and Ackermann performed ruthenium(II)‐catalyzed annulations of aromatic carboxylic acids with alkynes involving the activation of arene sp 2 C−H bonds in the presence of copper(II) as the oxidant but with an additive such as AgSbF 6 or KPF 6 . The efficient ruthenium(II)‐catalyzed annulation of aromatic carboxylic acids with alkynes by using molecular oxygen as the sole oxidant was just reported …”

A General Method to Diverse Cinnolines and Cinnolinium Salts

“…ortho-directed CÀH bond activation and subsequent functionalization to the directing groups. [7][8][9] By using different types of imines as the directing group, Fagnou, Chiba, and Cheng et al have independently developed versatile Rh III -catalyzed chelation-assisted C À H bond activation strategies to synthesize isoquinolines [8k,p] and isoquinolinium salts [8t] (Scheme 3). However, the utility of this concept for the synthesis of cinnolines and cinnolinium salts has not yet been documented.…”