Base-promoted [3+2] cycloaddition/aromatization cascade reaction under air: An approach to access perfluoroalkylated pyrrolo[2,1-a]isoquinolines

Synthesis of Pyrrolo[2,1-a]isoquinolines through Cu-Catalyzed Condensation/Addition/Oxidation/Cyclization Cascade

We have developed a copper-catalyzed synthesis of pyrrolo[2,1-a]isoquinolines with terminal alkynes, aldehydes, and tetrahydroisoquinolines. A variety of pyrrolo[2,1-a]isoquinolines have been prepared in 17-69% yield via a condensation/Mannich-type addition/oxidation/cyclization cascade sequence. Modifications through simple chemical transformations provided highly functionalized molecules containing a privileged framework.

Acetylenic Esters in Organic Synthesis

Activated acetylenic substrates such as acetylenic esters and alkyl propiolates are very important in organic synthesis. Due to their electron deficiency, these compounds are widely used in combinatorial and multicomponent reactions, enabling the synthesis of a large variety of novel compounds. In addition, these substrates are powerful Michael acceptors and convenient dienophiles and dipolarophiles in Diels–Alder and 1,3-dipolar cycloaddition reactions. The addition of different nucleophiles, primarily phosphorus, nitrogen or sulfur, to the triple bonds of these substrates produces key intermediates, such as Tebby and Huisgen zwitterions, which can lead to designing pathways toward the generation of spirocyclic and polycyclic compounds. This account highlights recent studies on the chemistry of acetylenic esters and their applications in organic synthesis.

1 Introduction

2 Synthesis of Acyclic and Monocyclic Compounds

3 Synthesis of Spirocyclic Compounds

4 Synthesis of Polycyclic Compounds

5 Conclusion

Recent progress in the synthesis of pyrrolo[2,1-a]isoquinolines

Pyrrolo[2,1-a]isoquinolines occur frequently in a large number of bioactive natural products and pharmaceutically important molecules. The synthesis of pyrrolo[2,1-a]isoquinoline derivatives is an easy and useful way to produce artificial molecules with potential applications. A huge number of excellent methodologies for constructing pyrrolo[2,1-a]isoquinolines have been reported in the last decade. This review summarizes the recent advances in this research field covering from 2011 to 2021.

Tungsten catalysed decarboxylative [3 + 2] cycloaddition aromatization: one-pot synthesis of trifluoromethyl-pyrrolo[2,1-a]isoquinolines with visible light irradiation

Trifluoromethyl-pyrrolo[2,1-a]isoquinolines, which are difficult to prepare via traditional methods, could be readily prepared via a tungsten-catalysed decarboxylative [3 + 2] cycloaddition aromatization process.

A Three-Component Synthesis of 3-Functionally Substituted 5,6-Dihydropyrrolo[2,1-a]isoquinolines

Synthesis of novel C3-substituted 5,6-dihydropyrrolo[2,1-a]isoquinolines via a three-component domino reaction of 1-aroyl-3,4-dihydroisoquinolines, terminal alkynes and CH-acids under microwave irradiation in dry acetonitrile is described. The method developed enables the obtainment of highly functionalized compounds with pharmacophore groups, which are potentially biologically active.

CuBr/NHPI co-catalyzed aerobic oxidative [3 + 2] cycloaddition-aromatization to access 5,6-dihydro-pyrrolo[2,1-a]isoquinolines

An efficient and enviromentally friendly CuBr/NHPI co-catalyzed aerobic oxidative [3 + 2] cycloaddition-aromatization cascade was realized with N-substituted tetrahydroisoquinolines and electron-deficient olefins. Under the mild conditions, the reaction proceeded smoothly and displayed excellent functional group tolerance, affording 5,6-dihydro-pyrrolo[2,1-a]isoquinolines in good to high yields. This protocol exhibits a broad substrate scope to both N-alkyl tetrahydroisoquinolines and dipolarophile substrates.