Diisopropylethylamine → tert-butyl 1,3-dioxo-2-[trans-2-phenylcyclopropyl]hexahydroimidazo[1,5-a]pyrazine-7(1H)-carboxylate

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Reaction Steps

To A3 in toluene (0.4M) was added dropwise trans-2-phenylcyclopropyl isocyanate (1.05 eq.). The mixture was stirred O/N at rt. DIPEA (1.5 eq.) was added and the mixture refluxed for 20 h. The organic phase was washed with phosphate buffer (2×200 mL, 0.75 M NaH2PO4, pH˜4.5) and the solvent removed under reduced pressure. The residue was purified by column chromatography on silica gel, eluting with 20-100% EtOAc/petroleum ether to give the title compound in 60% yield. MS (ES+) C20H25N3O4 requires 371, found: 394 (M+Na)+.

Provenance & Evidence