Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

Abstract

SummaryPyrrolo[2,1-a]isoquinoline alkaloids have been prepared via a visible light photoredox catalyzed oxidation/[3 + 2] cycloaddition/oxidative aromatization cascade using Rose Bengal as an organo-photocatalyst. A variety of pyrroloisoquinolines have been obtained in good yields under mild and metal-free reaction conditions.

Angled Vortex Fluidic Mediated Multicomponent Photocatalytic and Transition Metal‐Catalyzed Reactions

“…The choice of solvent and organic dye loading was based on successful literature photocatalytic reactions. [45,[52][53][54][55] Interestingly,t he reactionp roceeded smoothly and was deemed complete after only 30 min acrossa ll parameters,b ut 5000 rpm rotational speed and4 5 8 tilt angle produced the highest conversion,a t8 8% yield ( Figure 2). This is highly commensurate with literature reactions for the preparation of this molecule where reactions are typicallyc onducted for many hours with lower yields.…”

Construction and Functionalization of Heteroarenes by Use of Photoredox Catalysis

“…The same strategy was applied to tetrahydro‐β‐carbolines as 1,3‐dipole substrates and extended to continuous‐flow synthesis . An organocatalyzed version of this transformation with Rose Bengal photocatalyst was also developed . In the same context, a visible‐light‐induced photocatalytic oxidation/cycloaddition/aromatization cascade has been reported for the synthesis of imidazole derivatives from secondary amines and isonitriles …”

1,3-Dipolar cycloaddition between acetylenic dipolarophiles and sydnone-N-ylides as bis(1,3-dipoles)

“…33 The most versatile method of synthesis of pyrroloazines is the 1,3-dipolar cycloaddition reaction between heteroaromatic N-ylides and acetylenic dipolarophiles. [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] Herein we report the generation of sydnone-N-ylides as bis (1,3-dipoles) and their reactivity in the 1,3-dipolar cycloaddition reaction with acetylenic dipolarophiles. 1,3-Dipolar cycloaddition reaction of sydnone-N-ylides, as model bis (1,3-dipoles), with acetylenic dipolarophiles in 1,2-epoxybutane under reflux gave exclusively pyrroloazines containing a sydnone moiety that resulted by preferred reaction of the N-ylide 1,3-dipole with the acetylenic dipolarophiles.…”