The invention discloses a synthesis method and application of (3S)-1, 3-dimethyl
piperazine-2-
ketone, and the method comprises the following steps: S101, dissolving D-
alanine methyl
ester hydrochloride in a first
organic solvent, then adding alkali A and 2-methylaminoethanol, after addition, heating to 60-150 DEG C, carrying out stirring reaction for 8-20 hours, after the reaction is completed, carrying out first post-treatment on the reaction liquid, and carrying out second post-treatment on the reaction liquid, so as to obtain the (3S)-1, 3-dimethyl
piperazine-2-
ketone; the crude product of (R)-2-amino-N-(2-hydroxyethyl)-N-methyl propionamide is obtained; and S102, dissolving (R)-2-amino-N-(2-hydroxyethyl)-N-methylpropanamide in a second
organic solvent, then adding (1, 2-bis (ethoxycarbonyl) hydrazino) triphenylphosphonium
trifluoromethanesulfonate and alkali B, after addition, carrying out stirring reaction at 15-40 DEG C for 8-20 hours, and after the reaction is completed, carrying out secondary post-treatment on the reaction liquid to obtain the target (3S)-1, 3-dimethyl
piperazine-2-
ketone.