Access to Isoquinolines and Isoquinolin-3-ols via Rh(III)-Catalyzed Coupling/Cyclization Cascade Reaction of Arylimidates and Diazo Compounds

Abstract

A Rh(III)-catalyzed coupling/cyclization cascade reaction is described, which involves arylimidates and diazo compounds and proceeds via intermolecular C-C bond formation and subsequent intramolecular C-N bond formation. Mechanistic investigation revealed that the reaction is a two-step process: the initial Rh(III)-catalyzed coupling/cyclization proceeds very fast and the following dehydration is rather slow. The reaction provides a direct approach to isoquinolines and isoquinolin-3-ols without any oxidants.

Comprehensive Strategies for the Synthesis of Isoquinolines: Progress Since 2008

“…Few of the notable research works are mentioned below (Scheme 202). [211][212][213][214] Liu et al have put forth the synthesis of isoquinolinedione 341 via rhodium(III)-catalyzed CÀ H annulation of N-tosylbenzamides 297 with diazo compounds 94. The reaction conditions showed a dilemma with ortho-and para-substituted N-tosylbenzamides to obtain diverse range of isoquinolinedione in moderate to good yields (Scheme 203).…”

Realizing the Trifunctional Potential of Alkyl 4-Chloro-2-diazo-3-oxobutanoates: Convenient Assembly of 6,7-Dihydro-4H-[1,2,3]triazolo[5,1-c][1,4]thiazine Core

“…Compound 1 is rather densely functionalized, containing four contiguous potentially reactive centers: a labile chlorine, a ketone carbonyl, a diazo group, and an ester. It is therefore quite surprising that, according to literature reports, this reagent was mostly employed as a bifunctional -diazocarbonyl compound: in the synthesis of isocoumarins and -pyrones 7 as well as isoquinolones and pyridines 8 from benzamides (involving Rh III -catalyzed carbene C-H insertion), rather similar access to isoquinolines from arylimidates, 9 divergent synthesis of chromones and benzofurans via Rh III -catalyzed annulation of salicylaldehyde 10 and a series of related annulation reactions were reported in the last two years. [11][12][13] Treatment of 1 as bifunctional -diazocarbonyl reagent is showcased in its Rh II -catalyzed condensation with benzamides to give oxazoles 14 and Rh II -catalyzed 1,3-dipolar cycloaddition with enol ethers.…”

Diazo Compounds: Versatile Synthons for the Synthesis of Nitrogen Heterocycles via Transition Metal‐Catalyzed Cascade C–H Activation/Carbene Insertion/Annulation Reactions

“…Following this report, significant advances have been achieved recently for the synthesis of heterocycles in the area of transition metal‐catalyzed coupling of diazo compounds via C−H bond activation. Liu and co‐workers reported a Rh(III)‐catalyzed cascade C–H activation/coupling/cyclization reaction of arylimidates 57 and diazo compounds (Scheme ) . This reaction provides a new direct route to isoquinolines 58 and isoquinolin‐3‐ols 59 under oxidant‐free conditions.…”