Landiolol is prepared by the reaction of 2-(morpholine-4-carboxamido)ethanamino hydrochloride and (S)-(2,2-dimethyl-1,3-dioxolan-4-yl)methyl 3-(4-hydroxyphenyl)propanoate. The steps are as follows:
A suspension of (S)-(2,2-dimethyl-1,3-dioxolan-4-yl)methyl 3-(4-((2R)-3-chloro-2-hydroxypropoxy)phenyl)propanoate prepared according Example 3 (0.50 g, 0.00134 mol) in isopropanol (10 ml) is added with 2-(morpholine-4-carboxamido)ethanamino hydrochloride (18) (1.4 g, 0.00670 mol), heated to 30-35°C and dropwise added with 30% NaOH, keeping pH at 10-11.
The mixture is left under stirring at 35-40°C, monitoring by UPLC.
After completion of the reaction, ethyl acetate (20 ml) and water (20 ml) are added and the phases are separated.
The organic phase is added with water (20 ml) and adjusted to pH 3-4 with hydrochloric acid.
The phases are separated and the resulting aqueous phase is then adjusted to pH 10-11 with sodium hydroxide and re-extracted with ethyl acetate (20 ml).
The solvent is then evaporated off under reduced pressure to obtain 0.38 g (55.6%) of a pale yellow oil which solidifies in time to a pale yellow solid.