Synthetic Approaches to (Z)‐Thioaurones

Abstract

(Z)‐Thioaurones were prepared by the condensation of 1‐benzothiophen‐3‐ones or 3‐acetoxybenzothiophene with arylaldehydes under basic or acidic conditions. Their derivatives were also prepared by reducing 2‐benzoybenzothiophen‐3‐ones and subsequent dehydration, cyclization of α,β‐unsaturated 1‐(2‐methylsulfinyl)phenyl ketone, and coupling of β‐chlorobenzothiophenone with arylboronic acids using Pd catalyst. Furthermore, (Z)‐thioaurones were prepared by the direct cyclization of α‐(phenylthio)cinnamic acids, 5‐exo cyclization of 2′‐(methylthio)chalcones, incorporation of a sulfur atom to 2′‐nitrochalcones and aromatic substitution, and deprotection of S‐protected alkynones and subsequent cyclization. Moreover, thioflavanone‐1‐oxides underwent ring contraction with I2 or NaOAc/Ac2O to give (Z)‐thioaurones.

Heterocyclic Hemithioindigos: Highly Advantageous Properties as Molecular Photoswitches**

“…They possess a number of advantageous properties such as visible light responsiveness, considerable absorption differences between isomers, rigid and thus predictable structures, high thermal stability of metastable states, and straight forward synthetic access. [12] Mechanistic studies have already revealed a large influence of substitution on the photophysical and photochemical properties and allow to tune them much more consciously. [13] Consequentially HTIs have found their way into many different applications already, including molecular machines, [14] supramolecular chemistry, [15] chemical biology, [16] or multi-switches, [17] photosalient behavior, [18] and molecular logic.…”