Three-Component Fusion to Pyrazolo[5,1-a]isoquinolines via Rh-Catalyzed Multiple Order Transformation of Enaminones

Abstract

A facile and practical method for the synthesis of fused tricyclic pyrazolo[5,1-a]isoquinolines has been realized via the reactions of enaminones, hydrazine hydrochloride, and internal alkynes. By means of Rh catalysis, the extraordinary high-order bond functionalization, including the transformation of aryl C−H, ketone C�O, and alkenyl C−N bonds in the enaminones, marks the major feature of the cascade reactions. The results disclose the individual advantage of enaminones in the design of novel and efficient synthetic methods.

A C–H functionalization approach to diverse nitrogenous scaffolds through conjugate addition of catalytic allyliron nucleophiles

“…While some processes have capitalized on this phenomenon to produce new β-substituted α,β-unsaturated ketones, attempts to prepare β-amino ketones through conjugate addition are often plagued by formation of these compounds as side products. 47–52 Thus, the successful implementation of this strategy requires carbanion equivalents of high nucleophilicity while simultaneously demanding relatively mild conditions to ensure that the desired adduct survives the reaction conditions (Scheme 6).…”

Transition Metal‐Catalyzed Dual C−H Activation/Annulation Reactions Involving Internal Alkynes

“…3). [41] In this work, they used AgSbF 6 and PivOH as the additives. The nitrogen of the pyrazole ring acted as an auxiliary group to direct the ortho-CÀ H activation and annulation process.…”

Synthesis of pyrazoles from sulfonyl hydrazone and benzyl acrylate under transition-metal-free conditions

“…6 They are also widely found in building blocks of ligands for generating metallic complexes. 7 In addition, many marketed drugs contain pyrazole structural units, 8 such as Celecoxib ( A ), Acomplia ( B ), Zoniporide ( C ) and Rimonabant ( D ) as depicted in Fig. 1.…”