Synthesis of benzoindoloquinolizines via a Cu(I)-mediated C–N bond formation

Synthesis of 3‐Aminopyrido[2,1‐a]isoquinolin‐4‐one Derivatives via Condensation of Azlactones with 1‐Alkyl‐3,4‐dihydroisoquinolines

“…They react with 4-benzylideneoxazol-5(4H)-one as enamines to form 3-amino-2,3,6,7tetrahydro-4H-pyrido[2,1-a]isoquinolin-4-one amides [19,20g] which can be oxidized to 3-aminopyrido[2,1-a]isoquinolin-4one derivatives in low and moderate yield. [19] Herein, we reported on a one-step synthesis of new 3amino-6,7-dihydro-4H-pyrido[2,1-a]isoquinolin-4-one derivatives based on easy available azlactones 5-11 and 3,4dihydroisoquinolines 18 a-e, 19 a, 20 a, 21 a, 22 a.…”

“…The known methods for the synthesis of 3‐amino‐6,7‐dihydro‐4 H ‐pyrido[2,1‐ a ]isoquinolin‐4‐ones include multistep reactions [19] . A possibility to obtain 3‐aminopyridine‐2(1 H )‐one derivatives by reacting enamines with azlactone 5 has been previously reported [20a–h] …”

“…1‐Alkyl‐3,4‐dihydroisoquinolines can exist in two tautomeric forms, [21a–f] imine and enamine. They react with 4‐benzylideneoxazol‐5(4 H )‐one as enamines to form 3‐amino‐2,3,6,7‐tetrahydro‐4 H ‐pyrido[2,1‐ a ]isoquinolin‐4‐one amides [19,20g] which can be oxidized to 3‐aminopyrido[2,1‐ a ]isoquinolin‐4‐one derivatives in low and moderate yield [19] …”

Synthesis of Novel 13a‐(ω‐Aminoalkyl)‐8‐oxoberbines by Means of Reaction of Homophthalic Anhydride with 1‐Substituted 3,4‐Dihydroisoquinolines. An Unexpected Formation of a Pyrrolo[3,4‐i]berbindione

“…Compounds 8 and 9 can be regarded as β,β′‐, respectively, β,γ′—diamino acid derivatives, and as such, they are expected to possess biological activity or they could serve as starting materials for further functional groups transformations of the protoberberines. From the other hand, the versatility of 1‐substituted 3,4‐dihydroisoquinolines as synthons for the preparation of fused polyheterocyclics containing bridgehead nitrogen atom is demonstrated by this research once more.…”

Copper‐Catalyzed Indole Synthesis

“…The copper-catalyzed double amination of 2-(2-bromoalkenyl) bromobenzene (equation 4) could also employ CuOAc and CuTC (copper(I) thiophene-2-carboxylate) and other [54]. Other examples in this category of copper-catalyzed amination are syntheses of the carbazole alkaloids murrayaquinone-A and (±)-bismurrayaquinone-A [62], 3-aryl β-carbolin-1-ones [63,64], carbazoles from double C-N cyclization [65], pyrrolo [ [70], and extended π-conjugated heteroacenes [71]. Koenig described a similar indole-2-carboxylate preparation that involved condensation between 2-halobenzaldehydes and glycine amidoesters followed by copper-catalyzed indolization [57].…”