Synthesis
5-isopropyl-4,4’-dimethyldihydrofuran-2,3-dione 170.21g (1 mol) dissolved in methanol 1500g, fully stirred to dissolve, controlled temperature 0 to 55 , add calcium hydroxide 74.09g of 740.9g of propanetriol solution, stirring reaction for 8 hours, cooling 0 crystallization for 2 hours, filtration, to get ketovalentine calcium crude product 140g, molar yield 90%. Add 140g of ketovaline calcium crude product into 20% methanol aqueous solution, warm up to 55 to dissolve, cooling 0 crystallization for 2 hours, filtration, obtained ketovaline calcium crude product 123g, molar yield 87.8%. HPLC purity 99.9%.
