(-)Menthyl (-)-2-pyrrolidone-5-carboxylate (1R-(1alpha,2beta,5alpha))-2-Isopropyl-5-methylcyclohexyl 5-oxo-L-prolinate 64519-44-4 EINECS 264-935-8 L-Proline, 5-oxo-, (1R,2S,5R)-5-methyl-2-(1-methylethyl)cyclohexyl ester