Acetic Acid → 1'-(1,4-dioxaspiro[4.5]decan-8-yl)spiro[benzo[d][1,3]oxazine-4,4'-piperidin]-2(1H)-one

Participants

Reaction Steps

Spiro[4H-3,1-benzoxazine-4,4′-piperidin]-2(1H)-one (A4) (400 mg, 1.83 mmol) was suspended in anhydrous 1,2-dichloroethane (8.0 mL) and treated with 1,4-cyclohexanedione mono-ethylene ketal (viia) (429 mg, 2.75 mmol), glacial acetic acid (220 mg, 3.66 mmol), and sodium triacetoxyborohydride (776 mg, 3.66 mmol). The reaction flask was flushed with nitrogen and stirred for 60 hours at room temperature. The reaction was diluted with dichloromethane (25 mL), quenched with 1.0 N NaOH (10 mL), and stirred at room temperature vigorously for 30 minutes. The layers were separated and the aqueous layer was extracted once with dichloromethane (10 mL). The pooled organic layers were washed with water (1×25 mL) and saturated brine (1×25 mL), dried over Na2SO4 and filtered. The filtrate was concentrated under reduced pressure to afford crude 1′-(1,4-dioxaspiro[4.5]decan-8-yl)spiro[benzo[d][1,3]oxazine-4,4′-piperidin]-2(1H)-one (viiib) as a white solid. LC/MS m/z 359.2 [M+H]+, retention time 1.61 min (RP-C18, 10-99% CH3CN/0.05% TFA).

Provenance & Evidence