Ligand‐Controlled Palladium(II)‐Catalyzed Regiodivergent Carbonylation of Alkynes: Syntheses of Indolo[3,2‐c]coumarins and Benzofuro[3,2‐c]quinolinones

Abstract

Regiodivergent syntheses of indolo[3,2‐c]coumarins and benzofuro[3,2‐c]quinolinones through a controllable palladium(II)‐catalyzed carbonylative cyclization are established. The chemo‐ and regioselectivity are exclusively tuned by the ligand on the palladium catalyst. The rigid framework of the electron‐deficient ligand promotes the O‐attack/N‐carbonylation cyclization leading to benzofuro[3,2‐c]quinolinones, while a sterically bulky and electron‐rich ligand facilitates N‐attack/O‐carbonylation cyclization to generate indolo[3,2‐c]coumarins. Furthermore, various other nucleophiles are applicable for delivering a variety of indoloquinolinones, pyranoquinolones, and chromeno[3,4‐c]quinolinones in one step, and serves as a method for creating compound libraries for drug discovery.

Ligand‐Controlled Copper‐Catalyzed Regiodivergent Carbonylative Synthesis of α‐Amino Ketones and α‐Boryl Amides from Imines and Alkyl Iodides

“…[10] Additionally, several other original regioselective transformations on carbonylation have been established in recent years as well. [11] Despite these achievements, regiodivergent carbonylative conversion of C = N double has rarely been reported. [12] This is due to the polarized imine (C = N) groups place a part of positive charge at the carbon atom, making the carbon positive (electrophilic)-attracted by negatively charged nucleophiles (Scheme 1 b).…”

2‐(Alkynyl)anilines and Derivatives — Versatile Reagents for Heterocyclic Synthesis

“…A great opportunity for regiodivergent transformation of 2‐hydroxy‐2’‐amino‐diphenylacetylenes 153 was discovered by Jiang and co‐workers [147] . In this case, a ligand determines the direction of a carbonylative cyclization.…”

One-Pot Synthesis of 4H-Pyrano[3,2-c]coumarin Derivatives Catalyzed by Deep Eutectic Solvent

“…21 In addition, tetrabutylammonium bromide (TBAB) can be used to catalyze the reaction of 4-hydroxycoumarin with ethyl benzylidenecyanoacetate to synthesize pyrano [3,2-c]coumarin derivatives (Scheme 1b). 22 There have been many related reports on synthetic methods for these compounds using many catalysts, such as metal catalysts (Fe, Cu, Pd), [23][24][25][26][27][28] NaBr, 29 ZnO, [30][31][32] hexamethylenetetramine, 33 and potassium phthalimide. 34 The major disadvantages of using these catalysts are unsatisfactory yields, long reaction times, complicated operations, and high cost.…”