Towards cleaner PolarClean: efficient synthesis and extended applications of the polar aprotic solvent methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate

As a result of recent efforts in green solvent selection, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, sold under the brand name Rhodiasolv PolarClean, has received considerable scientific and industrial attention as a possible non-toxic replacement for common polar aprotic solvents. However, the multicomponent nature and multi-step synthesis of this solvent remains an obstacle for its more widespread use and niche applications. In this work, a retrosynthetic approach was taken to identify novel shorter synthetic routes in alignment with green chemistry principles. High purity methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate was obtained in novel single-step reactions via two different base-catalysed Michael additions from readily available building blocks. The more advanced synthetic route shows great potential owing to the swift (30 min), solvent-free reaction and catalytic amounts of base (