Ruthenium(II)-Catalyzed Redox-Neutral Oxidative Cyclization of Benzimidates with Alkenes with Hydrogen Evolution

Abstract

1H-Isoindoles and 2H-isoindoles are synthesized via a ruthenium-catalyzed oxidant-free cyclization of benzimidates with alkenes at room temperature with the liberation of H. Later, 1H-isoindoles were converted into nitrogen-containing heterocycles. The proposed reaction mechanism was strongly supported by experimental evidence and DFT calculations.

Ruthenium (II)‐Catalyzed Oxidant‐Free Coupling/Cyclization of Benzimidates and Sulfoxonium Ylides to Form Substituted Isoquinolines

“…To better understand the mechanism of this transformation, control experiments were designed and conducted (Scheme ). First, when benzimidate d5– 1 a was used instead of 1 a under the optimized conditions, desired deuterated product d– 3aa was obtained in 71% yield with 29% hydrogen incorporation at the C‐8 position of the product, indicating a reversible C−H activation process ,. Next, the reaction of a 1 : 1 mixture of 1 a and d5– 1 a produced both 3 aa and d– 3 aa in 45% yield.…”

Ortho‐Functionalization of Benzimidates and Benzamidines

“…In 2017, Jeganmohan and co‐workers realized the coupling of benzimidates ( 59 ) with alkenes ( 60 ) to provide isoindoles ( 61 ) (Scheme 26). [29] Using [RuCl 2 ( p ‐cymene) 2 ] (5 mol %), Adm‐1‐COOH (0.5 equiv) in EtOH (1.0 mL) at rt for 8–24 h, electron‐donating as well as electron‐withdrawing group substituted benzimidates reacted with acrylates to deliver the desired products. However, unsymmetrical benzimidates gave regioisomeric mixtures with a combined yield of 72 %.…”

Reaching Green: Heterocycle Synthesis by Transition Metal‐Catalyzed C−H Functionalization in Sustainable Medium

“…Jeganmohan and co-workers reported aR u-catalyzeda nnulation reaction of benzimidates 31 with activated alkenes 14 for the synthesis of isoindoles 32 (Scheme 12 a). [39] The reaction proceeded in the absence of oxidantw ith the liberation of hydrogen in less-toxicethanol solvent at room temperature. Similarly,t he annulation of N-tosylamides 4 with activated alkenes 14 provided an efficient method to build isoindolinones 33 as demonstrated by Ackermann and co-workers( Scheme12b).…”

“…Jeganmohan and co‐workers reported a Ru‐catalyzed annulation reaction of benzimidates 31 with activated alkenes 14 for the synthesis of isoindoles 32 (Scheme a) . The reaction proceeded in the absence of oxidant with the liberation of hydrogen in less‐toxic ethanol solvent at room temperature.…”