Acetone → N-((1'-benzyl-1-(5-ethyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)spiro[indoline-3,4'-piperidine]-4-yl)methyl)propan-2-amine

Participants

Reaction Steps

(1′-Benzyl-1-(5-ethyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)spiro[indoline-3,4′-piperidine]-4-yl)methanamine tris(2,2,2-trifluoroacetate) (606 mg, 0.762 mmol) was stirred in a solution of acetone (0.280 mL, 3.81 mmol) and DCE (5 mL) for 15 minutes. NaBH(OAc)3 (323 mg, 1.52 mmol) was added in one portion and resulted in vigorous evolution of gas. After 1 hour at room temperature, LCMS suggested complete conversion to the desired isopropylamine. The reaction was concentrated and partitioned between EtOAc and 10% aqueous K2CO3. The organic was washed with brine, dried over Na2SO4 and concentrated to a crude residue. The racemic crude was purified by silica gel chromatography (gradient: 5-100% (80 DCM: 19 MeOH: 1 NH4OH)/DCM). Purification provided N-((1′-benzyl-1-(5-ethyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)spiro[indoline-3,4′-piperidine]-4-yl)methyl)propan-2-amine (68 mg, 0.137 mmol, 18.0% yield) as an oil. 1H NMR (CDCl3, 400 MHz) δ 8.62 (s, 1H), 7.27-7.33 (m, 5H), 7.24 (m, 1H), 7.18 (t, 1H), 6.96 (d, 1H), 3.95 (m, 4H), 3.54 (s, 2H), 3.27 (m, 1H), 2.84-2.99 (m, 5H), 2.63 (dt, 1H), 2.03-2.31 (m, 4H), 1.86 (m, 1H), 1.70 (dd, 2H), 1.42 (m, 2H), 1.15-1.119 (m, 7H), 0.78 (t, 3H). MS (APCI+) [M+H]: 496.3. Separation of isomers was conducted by preparative HPLC using a Chiralpak AD-H column (4.6×100 mm). The compound was eluted with 25% methanol/water (0.1% TEA additive) at 3 mL/min and 120 bars.

Provenance & Evidence