Selenonium Salt as a Catalyst for Nucleophilic Substitution Reactions in Water: Synthesis of Thiocyanites and Selenocyanates

Abstract

Organothiocyanates and selenocyanates are valuable compounds, both in terms of functional group interconversion and due to their biological activities. In this contribution, we report the synthesis of a series of these important substances in a mixture of water and dimethyl carbonate (20/1 proportion) using potassium thio- or selenocyanates salts and organic bromides. The key to the effectiveness of the reaction is a chalcogen bond interaction between a selenonium salt catalyst and the organic substrate.

Keywords: chalcogen bond; organocatalysis; selenocyanate; selenonium salt; thiocyanate.

Figure 1

Structure of biologically active organothiocyanates and organoselenocyanates.

Scheme 1

Evaluation of selenonium salt C7 as a catalyst.

Scheme 2

(a) Chalcogen bond formation between selenonium salt and benzyl bromide. (b) Correlation of the ¹H NMR chemical shift of hydrogens adjacent to selenium and concentration of benzyl bromide.