Rh(III)‐Catalyzed Synthesis of Multisubstituted Isoquinolines from Benzylamines and Diazo Compounds

Abstract

Multisubstituted isoquinolines have been prepared by Rh(III)catalyzed cyclization of benzylamines with diazo compounds via aryl CÀH bond activation using molecular oxygen from air as an oxidant. This method features mild reaction conditions, simple catalytic system, tolerance of a broad range of substrates, high efficiency and regioselectivity.

Transition‐Metal‐Catalyzed C−H Bond Functionalization of Arenes/Heteroarenes via Tandem C−H Activation and Subsequent Carbene Migratory Insertion Strategy

“…[105] The protocol features high selectivity in the 3-& 4-positions of isoquinolines, acting as a A similar methodology, reported by Cui and co-workers in 2017, leads to the synthesis of multi-substituted isoquinolines using Rh(III) as the catalyst and atmospheric oxygen as the oxidant (Scheme 35b). [106] The methodology features mild reaction conditions and a wide-functional group tolerance with high efficiency and regioselectivity. A few complimentary examples bring forth the variability of the substrate scope thus opening prospects for various natural products synthesis.…”

Free‐Amine‐Directed Iridium‐Catalyzed C−H Bond Activation and Cyclization of Naphthalen‐1‐amines with Diazo Compounds Leading to Naphtho[1,8‐bc]pyridines

“…This reaction relies on the coordination of the lone pair electrons of the N atom on the free amino groups. Subsequently, Cheng, Li, and Cui reported similar Rh(III)‐catalyzed annulations of benzylamines with diazo compounds toward isoquinolines (Scheme b). In these three reactions, benzylamines needed to react with acetone or be oxidized to imines, and the in situ formed imines have been proposed to be the real directing group.…”

Comprehensive Strategies for the Synthesis of Isoquinolines: Progress Since 2008

“…[203] The above method was later improvised by Zhang et al by eliminating the need of additive to synthesize 3,4-dihydroisoquinolines 105 in good yields (Scheme 199). [204] Wang et al [205] Chu et al [206] and Lin et al [207] have developed a similar Rh-catalyzed annulation of benzylamines and diazo compounds. He et al have demonstrated Rh-catalyzed intramolecular reaction of bromonium ylides, which are obtained upon reaction of benzyl bromide 333 and αimino carbene to access 4-bromo-1,2-dihydroisoquinolines 334 (Scheme 201).…”

“…Chu et al [206] . and Lin et al [207] . have developed a similar Rh‐catalyzed annulation of benzylamines and diazo compounds.…”