(S)-1-Boc-3-methylpiperazine → HCID 59670996, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of (5R)-4-chloro-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-7-yl acetate (0.75 g, 3.3 mmol) in NMP (10 mL) was added (S)-tert-butyl 3-methylpiperazine-1-carboxylate (1.0 g, 5.0 mmol). The mixture was heated to 125° C. for 60 hours. After cooling, the mixture was diluted with ethyl acetate (200 mL) and washed with water (6×100 mL). The organic phase was dried and concentrated. The residue was purified by silica gel chromatography, eluting with ethyl acetate to give (S)-tert-butyl 4-((5R)-7-acetoxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)-3-methylpiperazine-1-carboxylate (0.775 g, 60%). 1H NMR (CDCl3, 400 MHz) δ 8.60-8.59 (d, 1H), 6.07-5.89 (m, 1H), 4.73-4.60 (m, 1H), 4.30-3.80 (m, 3H), 3.60-3.35 (m, 1H), 3.22 (m, 1H), 3.02 (br, 1H), 2.78 (m, 1H), 2.35-1.60 (m, 5H), 1.49 (s, 9H), 1.32-1.20 (m, 6H). MS (APCI+) [M+H]+391. The resulting mixture of diastereomers was purified by chiral separation by HPLC (Chiralcel ODH column, 250×20 mm, 15 mL/min, Hexane/EtOH 50:50). The first peak (RT=3.864 min) gave (S)-tert-butyl 4-((5R,7R)-7-acetoxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)-3-methylpiperazine-1-carboxylate (0.281 g, 36%) and the second peak (RT=5.064 min) gave (S)-tert-butyl 4-((5R,7S)-7-acetoxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)-3-methylpiperazine-1-carboxylate (0.389 g, 50%). Treatment of the (S)-tert-butyl 4-((5R,7R)-7-acetoxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)-3-methylpiperazine-1-carboxylate with HCl in dioxane (4M, 2 ml) gave the (5R,7R)-5-methyl-4-((S)-2-methylpiperazin-1-yl)-6,7-dihydro-5H-cyclopenta[d]pyrimidin-7-ol dihydrochloride in quantitative yield.

Provenance & Evidence