2-Chloro-N,N-dimethylethylamine → Deacetyldiltiazem

Participants

Reaction Steps

A 5-L three-necked flask equipped with a heating mantle, a mechanical stirrer and a condenser was charged with 162 g (0.54 mol) of (+)-(2S,3S)-2,3-dihydro-3-hydroxy-2-(4-methoxyphenyl)-1,5-benzothiazepin-4(5H)-one and then 1 L of ethyl acetate. After stirring to dissolve the solution, 100 g (0.694 mol) of dimethylaminoethyl chloride.HC1 was added in one portion followed by 300 g (2.16 mol) of finely ground K2CO3 and 5 mL of H2O. (The 5 ml. of water was essential to cause a reaction between the phases, while addition of much more water would have resulted in gummy mixture that was difficult to filter.) This heterogeneous mixture was rapidly stirred at reflux for 5 hours. By thin layer chromatography (8:1, CH2C12 -MeOH, short wave UV), reaction was complete and therefore the mixture was allowed to cool to room temperature, filtered through a sintered glass funnel and washed with 100 mL 1:1 hexanes-ethyl acetate. The solvent was evaporated and on standing the oil crystallized. Recrystallization from ether gave 140 g (70%) of colorless crystalline (+)-(2S,3S)-5-[2-(dimethylamino)ethyl]-2,3-dihydro-3-hydroxy-2-(4-methoxyphenyl)-1,5-benzothiazepin-4(5H)-one, m.p. 79-81° C., [α]D20=+ 156.4°(C=1.0; CHC13).

Provenance & Evidence