Synthesis of Isoquinolines through Ir^III‐Catalyzed C–H Activation/Annulation from Benzimidates with Hydroxylisopropylalkynes

Abstract

An IrIII‐catalyzed cascade reaction consisting of C–H activation/annulation of benzimidates with hydroxylisopropylalkynes is reported. A broad range of isoquinolines has been prepared in one step with good functiona‐group tolerance and high efficiency.

Comprehensive Strategies for the Synthesis of Isoquinolines: Progress Since 2008

“…Liu et al. have reported the Ir(III)‐catalyzed C−H activation followed by annulation of benzimidates 86 with hydroxylisopropylalkynes 57 to obtain isoquinolines 186 [118] . The present method rely on the same strategy followed by Anukumar et al [119] .…”

“…[117] Liu et al have reported the Ir(III)-catalyzed CÀ H activation followed by annulation of benzimidates 86 with hydroxylisopropylalkynes 57 to obtain isoquinolines 186. [118] The present method rely on the same strategy followed by Anukumar et al [119] as both the groups have used the same kind of substrates while catalyst being different, latter used Ru-catalyst. Liu group have employed benzimidates as model substrate.…”

Recent approaches for the synthesis of pyridines and (iso)quinolines using propargylic Alcohols

“…In 2018, a one-step synthesis of isoquinoline derivatives 181 through an Ir( iii )-catalyzed cascade C–H activation–annulation of benzimidates 182 with propargylic alcohols 183 was reported by the research group of Cao and Shi (Scheme 33A). 54 The reaction conditions showed compatibility for a large range of functional groups. According to the proposed mechanism (Scheme 33B), benzimidate 182 and [Cp*IrCl 2 ] 2 coordinate to form an intermediate 184 through an ortho C–H activation, which upon reaction with Piv-alcohol converted into an active Iridium complex 185 .…”

Rhodium(III)-Catalyzed Cascade Reactions of Imines/Imidates with 4-Hydroxy-2-alkynoates to Synthesize Regioselective Furanone-Fused Isoquinoline Scaffolds

“…The authors suggested the metal catalysts and hydroxyl group present at the tertiary propargyl alcohol control the regioselectivity. The Ackermann and Cao groups utilized similar strategies for the regioselective synthesis of isoquinolines using benzimidate as a directing group (Scheme e) . Later, the Jeganmohan group revealed the synthesis of isoquinolines, via an allene intermediate formation, through a β-oxygen elimination (Scheme f) .…”