Ir(I)‐Catalyzed Synthesis of (<i>E</i>)‐4‐Benzylidenylacridines and (<i>E</i>)‐2‐Styrylquinoline‐3‐carboxamide through Sequential Suzuki–Miyaura Coupling, Dehydrogenative Friedländer Reaction, and sp<sup>3</sup>‐C–H Activation
Soda Prameela, Fazlur‐Rahman Nawaz Khan
Abstract
An efficient one‐pot strategy evolved in the synthesis of (E)‐4‐benzylidenylacridin‐1(2H)‐ones, ( 4 or 9 ) (E)‐2‐styryl quinoline‐3‐carboxamides ( 5 or 10 ) by sequential Suzuki–Miyaura coupling‐dehydrogenative Friedländer‐sp 3 C–H activation. The 2‐amino‐5‐chloro benzhydrol 1 , aromatic alcohol 2 or 6 ketones 3 or 3' , and phenylboronic acid 7 underwent a smooth reaction in a basic deep eutectic solvent consisting of K 2 CO 3 and ethylene glycol (DES‐1,1:1). DES‐1 could enable the Pd‐catalyzed Suzuki coupling reaction of 6 , as well as the rapid oxidation of primary, secondary, and Suzuki coupled primary alcohols ( 2 , 1 , and 8 ) in the presence of an iridium catalyst and 1,10‐phenanthroline. The acidic DES‐2 (dimethyl urea/tartaric acid, 7:3) assists the Friedländer annulation and subsequent sp 3 ‐C–H functionalization resulting in (E)‐4‐benzylidenylacridin‐1(2H)‐ones ( 4 or 9 ) and (E)‐2‐styryl quinoline‐3‐carboxamides ( 5 or 10 ).