An Efficient Selectfluor-Mediated Oxidative Thio- and Selenocyanation of Diversely Substituted Indoles and Carbazoles

Rodrigo Abonia,Luisa F Gutierrez,Kenneth K Laali,Sebastián Correa Smits,Angela T Zwarycz

doi:10.1155/2019/1459681

Abstract

A facile Selectfluor-mediated oxidative method for direct introduction of SCN and SeCN groups into diversely substituted indoles and carbazoles is described, by employing readily available thiocyanate and selenocyanate salts, and the scope of the method is underscored by providing 24 examples. The feasibility to sequentially introduce SCN followed by SeCN on a carbazole framework and to synthesize the corresponding S-tetrazole and Se-tetrazole derivatives is also demonstrated.

Highlights

Selectfluor,1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), known as F-TEDABF4) is a safe, bench stable, nontoxic, and highly reactive onium dication salt that delivers an equivalent of electrophilic or radical fluorine [1, 2]. It is widely used in the synthesis of organofluorine compounds [3,4,5,6,7,8], but it serves as a versatile catalyst and mediator in transformations involving oxidizable functional groups [9,10,11,12,13]
In relation to other studies in our laboratory on the synthesis of heterocyclic curcuminoids and their antitumor properties [57], we were especially interested in the indole backbone bearing isomeric formyl substituents
HRMS analyses were performed on a Finnigan Quantum ultra-AM in electrospray mode using methanol as solvent

Summary

Introduction

Selectfluor,1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate), known as F-TEDABF4) is a safe, bench stable, nontoxic, and highly reactive onium dication salt that delivers an equivalent of electrophilic or radical fluorine [1, 2]. For that reason, it is widely used in the synthesis of organofluorine compounds [3,4,5,6,7,8], but it serves as a versatile catalyst and mediator in transformations involving oxidizable functional groups [9,10,11,12,13]. Developing new and broad-based protocols for direct introduction of SCN and SeCN moieties into organic structures, in particular those motifs that are important for medicinal chemistry as building blocks of pharmaceuticals, continues to be relevant

Methods

Results

Conclusion