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. Author manuscript; available in PMC: 2020 Oct 30.
Published in final edited form as: Bioorg Med Chem Lett. 2010 Dec 28;21(4):1141–1145. doi: 10.1016/j.bmcl.2010.12.109

Scheme 1.

Scheme 1.

Synthesis of spirodiketopiperazines 6a–d. Reagents and conditions: (a) 2-(4-morpholinyl)-ethyl isonitrile, MeOH, 55 °C; (b) concd HCl, 55 °C; (c) AcOH/toluene, 80 °C; (d) H2, Pd(OH)2/C, EtOH, 50 °C, then 4 N HCl/AcOEt, 60–90% yield in four-steps; (e) 4-(4-formylphenoxy)benzoic acid, NaBH(OAc)3, AcOH, DMF and then 4 N HCl/AcOEt, 50–90% yield.