A simple and efficient KI promoted sulfur activation‐insertion/de‐nitration strategy has been developed for the synthesis of β‐carboline C1 tethered 2‐acylbenzothiophenes via one‐pot assembly of 1‐acetyl β‐carbolines (an alkaloid based scaffold), 2‐nirobenzaldehydes and elemental sulfur. This expeditious reaction proceeds through the formation of β‐carboline linked nitro‐chalcones followed by embodiment of elemental sulfur to generate the multifunctional β‐carboline linked benzothiophene derivatives. The highlighted features of this efficient methodology are transition metal‐free conditions, use of inexpensive and non‐toxic catalyst, easy procedure, short reaction time, and broad substrate scope with good yields. The scope of this protocol has been extended for the synthesis of a range of novel compounds with significant diversity.
A transition metal‐free, base‐mediated efficient synthesis of novel β‐carboline C1(3) tethered triazines has been accomplished by using β‐carboline alkaloid; Kumujian C as a template for reaction with readily available amidines. The strategy has been found compatible with diverse 1(3)‐formyl β‐carbolines and amidines, providing access to wide variety of novel β‐carboline linked 1,3,5‐triazines in good to excellent yields. The methodology is also amenable to gram scale synthesis of triazines. The presented methodology features sustainable reaction conditions, clean and simple methodology, low environmental impact, wide substrate scope and high atom economy with good to excellent yields. Moreover, the light emitting properties of these fluorescent β‐carboline linked triazine derivatives were investigated for the first time where quantum yield (ΦF) up to 60% was obtained.
An operationally simple and metal-free approach is described for the synthesis of pyrazole-tethered thioamide and amide conjugates. The thioamides were generated by employing a three-component reaction of diverse pyrazole C-3/4/5 carbaldehydes, secondary amines, and elemental sulfur in a single synthetic operation. The advantages of this developed protocol refer to the broad substrate scope, metal-free and easy to perform reaction conditions. Moreover, the pyrazole C-3/5-linked amide conjugates were also synthesized via an oxidative amination of pyrazole carbaldehydes and 2-aminopyridines using hydrogen peroxide as an oxidant.
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