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The general procedure for the synthesis of 1'H-spiro[piperidine-4,4'-quinazolin]-2'(3'H)-ones was carried out as follows, using 1-benzyl-1'H-spiro[piperidine-4,4'-quinazolin]-2'(3'H)-ones as starting material: 1-benzyl-1'H-spiro[piperidine-4,4'-quinazolin]-2'(3'H)-ones (1.00 g) were dissolved in degassed methanol (50 ml ), 6N hydrochloric acid (2.0 ml) was added followed by 10% palladium carbon catalyst (150 mg). The reaction mixture was placed in a Parr hydrogenation unit and the reaction was shaken at 60 psi hydrogen pressure overnight. The progress of the reaction was monitored by LC/MS and the reaction was found to be incomplete. The 10% palladium carbon catalyst (200 mg) was added additionally and the reaction was continued with oscillation under the same conditions for 2 days. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated to afford the target product 1'H-spiro[piperidin-4,4'-quinazolin]-2'(3'H)-one (531 mg, 64% yield). Mass spectrometry analysis showed a molecular ion peak of 218.12 (MH+).

[1] Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 14, p. 4719 - 4722
[2] Patent: WO2003/104236, 2003, A1. Location in patent: Page 58
[3] Patent: US2005/215576, 2005, A1. Location in patent: Page/Page column 19