alpha Lipoic acid → Lipoic acid

Diisopropylethylamine (DIPEA) (anhydrous, 4.3 ml, 24.2 mmol) was added to a solution of EDC.HCl (604 mg, 3.15 mmol) in dichloromethane (15 ml) and stirred for 10 minutes. N-hydroxysuccinimide (390 mg, 3.39 mmol) was added followed by DL-lipoic acid (500 mg, 2.43 mmol). The reaction mixture was stirred in an ice bath for half an hour and then slowly continued overnight under room temperature. The reaction mixture was washed with HCl (5% v/v, 25 ml×2) and water (50 ml×3). The organic layer was dried over Na2SO4, filtered and concentrated. The crude residue was purified by silica gel column chromatography (ethylacetate/hexane=2:1) (618 mg, 85%); 1H-NMR (CDCl3) 1.62-1.98 (7H, m), 2.29-2.47 (1H, m), 2.69 (2H, t, J=7.4), 3.02 (4H, s, succinimidyl CH2×2), 3.21-3.28 (2H, m), 3.60-3.65 (1H, m); ESI-MS m/z calcd for C12H17NO4S2: 303.2518. found: 304.1861 [M+1].

1. stirringThe reaction mixture was stirred in an ice bath for half an hour
2. customslowly continued overnight
3. customunder room temperature
4. washThe reaction mixture was washed with HCl (5% v/v, 25 ml×2) and water (50 ml×3)
5. dry with materialThe organic layer was dried over Na2SO4
6. filtrationfiltered
7. concentrationconcentrated
8. customThe crude residue was purified by silica gel column chromatography (ethylacetate/hexane=2:1) (618 mg, 85%)

ORD record

ord-b6821500b4e0439bbfaf532de6432789

Source dataset

uspto-grants-2015_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09006458B2