Clicking Renewable Resources: Thiol-ene Additions as a Versatile Tool for Terpene Modification

The utilization of renewable resources for the synthesis of new platform chemicals has been accepted as a great challenge in order to contribute to a sustainable development [1,2]. Terpenes are found in many essential oils and represent a sustainable and versatile chemical feedstock [3]. α- and β-Pinene are the major components of wood turpentine and can be obtained from the resinous sap of pine trees by steam-distillation, whereas limonene can be obtained as a byproduct of the citrus industry. In contrast to many other terpenes, pinenes and limonenes are abundant and inexpensive natural compounds that are real building blocks for the synthesis of new important chemicals [3].
Known chemical transformations of these renewables include, for instance, isomerizations, epoxydations, or hydration reactions in order to obtain products for the fragrance industry. Thiol-ene addition reactions, on the other hand, were not studied in detail with these compounds, even if the first reports date back more than 100 years [4]. Today, thiol-ene addition reactions are considered as click reactions and are versatile tools for the preparation of value added chemical intermediates [5,6]. Here, we report on the addition of thiol compounds to β-pinene and (R)-limonene under solvent free conditions. High conversions and isolated yields of the desired compounds were achieved, confirming that the preparation of renewable monomers and polymers from this feedstock is possible in a sustainable fashion.

References:
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