[N:1]1([C:7]([O:9][C:10]([CH3:13])([CH3:12])[CH3:11])=[O:8])[CH2:6][CH2:5][NH:4][CH2:3][CH2:2]1.Cl.O1CCOCC1.[S-:21][C:22]#[N:23]>C1COCC1.O>[NH2:23][C:22]([N:4]1[CH2:5][CH2:6][N:1]([C:7]([O:9][C:10]([CH3:13])([CH3:12])[CH3:11])=[O:8])[CH2:2][CH2:3]1)=[S:21]1,1-Dimethylethyl 1-piperazinecarboxylate (24 g, 129 mmol) in THF (1 L) was treated with 4N HCl in dioxane (32.2 mL, 129 mmol)), and thiocyanate (12.52 g, 129 mmol) dissolved in minimal amount of water was added. After stirring at rt overnight, the volatiles were removed under reduced pressure. The residue was taken up in MeOH and filtered to remove inorganic salts and the solvent removed in vacuo and the cycle was repeated 3 more times. Then twice taken up in DCM and filtered and concentrated to give the title compound of Step A (29 g, 92% yield). 1H NMR (400 MHz, DMSO-d6) δ ppm 8.74 (br. s., 2H), 3.50 (br. s., 4H), 3.07 (t, J=5.0 Hz, 4H), 1.40 (s, 9H).
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