反应详情

Scheme 3 shows the synthesis of intermediate, oxalate salt of (S)-2-hydroxy-1-(piperazin-1-yl)propan-1-one V from (S)-2-hydroxypropanoic acid (L-lactic acid) 1. Acetylation of 1 gave (S)-2-acetoxypropanoic acid 2, followed by treatment with a chlorinating reagent, such as oxalyl chloride, to give acid chloride, (S)-1-chloro-1-oxopropan-2-yl acetate 3 (Example 6). Reaction of 3 with the dihydrochloride salt of 1-benzylpiperazine in dichloromethane in the presence of triethylamine gave (S)-1-(4-benzylpiperazin-1-yl)-1-oxopropan-2-yl acetate 4 (Example 7). Hydrolysis of the acetate of 4 with lithium hydroxide gave (S)-1-(4-benzylpiperazin-1-yl)-2-hydroxypropan-1-one 5 (Example 8), followed by hydrogenation to remove the N-benzyl group to give (S)-2-hydroxy-1-(piperazin-1-yl)propan-1-one 6 (Example 9). The oxalate salt was formed from 6 with oxalic acid in ethanol and tetrahydrofuran to give V (Example 9).