Formaldehyde → (S)-2-Benzyl-4-(3-cyclopentyloxy-4-methoxy-phenyl)-1-methylpiperazine

Participants

Reaction Steps

A solution of (S)-3-Benzyl-1-(3-cyclopentyloxy-4-methoxy-phenyl)-piperazine (Example 2) (73 mg, 0.2 mmol) in CH2Cl2 (5 mL) was treated with a 37% aqueous formaldehyde solution (16.4 uL, 0.22 mmol) and stirred for 5 min after which time solid sodium triacetoxyborohydride (64 mg, 0.3 mmol) was added. The suspension was then stirred for 3 hr then quenched with a saturated aqueous NaHCO3 solution (2 mL). The organic component was separated, dried over MgSO4, filtered, and evaporated to an oil which was purified by silica gel flash chromatography with 5% MeOH/CH2Cl2 as eluant to afford product as a burgundy oil (69 mg, 91%). 1H NMR (CDCl3) 1.54-1.61 (m, 2H), 1.77-1.85 (m, 6H), 2.57 (s, 3H), 2.60-2.67 (m, 3H), 3.02-3.13 (m, 3H), 3.22-3.32 (m, 2H), 3.76 (s, 3H), 4.59-4.62 (m, 1H), 3.76 (s, 3H), 4.59-4.62 (M, 1H), 6.30 (dd, J=8.6, 2.9, 1H), 6.35 (d, J=8.6, 1H), 7.20-7.33 (m, 5H). 13C NMR 24.2 (CH2), 33.0 (CH2), 36.3 (CH2), 42.9 (CH3), 50.2 (CH2), 55.0 (CH2), 55.1 (CH2), 56.8 (CH3), 63.7 (CH), 80.4 (CH), 106.2 (CH), 107.8 (CH), 113.2 (CH), 126.4 (CH) 128.6, 129.5 (CH), 139.0 (CH), 144.5, 146.1, 148.4. LC/MS 5.10 min, [M+1]+ 381.

Provenance & Evidence