Lithium diisopropylamide → tert-Butyl 4-[2-(4-methyl-1-oxo-1,3-dihydro-2-benzofuran-5-yl)-2-oxoethyl]-3-oxopiperazine-1-carboxylate

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Reaction Steps

To a THF solution of tert-Butyl 3-oxopiperazine-1-carboxylate (164 mg, 0.82 mmol) was dropped LDA (0.37 ml, 0.74 mmol) at −78° C. After stirring the solution for 15 minutes, a THF solution of 5-(bromoacetyl)-4-methyl-2-benzofuran-1(3H)-one (200 mg, 0.74 mmol) was added into the reaction. TLC showed formation of a new spot right away. LC confirmed the desired alkylation product. The product was purified by MPLC to afford tert-Butyl 4-[2-(4-methyl-1-oxo-1,3-dihydro-2-benzofuran-5-yl)-2-oxoethyl]-3-oxopiperazine-1-carboxylate. LC-MS (IE, m/z): 389 [M+1]+. The resulting solid was further treated with TFA to remove the BOC group. The crude material was dissolved in aqueous sodium bicarbonate, extracted with Chloroform-IPA (3:1) three times, dried over sodium sulfate, and concentrated to furnish the free base of 1-[2-(4-Methyl-1-oxo-1,3-dihydro-2-benzofuran-5-yl)-2-oxoethyl]piperazin-2-one.

Provenance & Evidence