Applying Green Metrics to Eco-Friendly Synthesis of Sulfur-Substituted Conjugated Dienes Based on Atom-Economic Hydrothiolation

An efficient two-step procedure to get synthetically useful sulfur-functionalized dienes is evaluated. The overall transformation can be classified as an atom-economic hydrothiolation of alkynes followed by elimination of water at the dehydration step. Taking the alkynes hydrofunctionalization reaction as a representative example, critical analysis from the point of view of quantitative green metrics was carried out and key stumbling blocks in the area of atom-economic transformations were discussed. Ecological acceptability of the whole process was assessed by thorough examination of the yields and careful adjustment of the synthetic conditions, considering the opportunities for waste minimization. Careful optimization of the reaction conditions was followed by selection of environmentally friendly protocols for accessing pure product. Green metrics of synthetic procedures as well as different isolation techniques (column chromatography, dry column chromatography, extraction, and distillation) were compa...