Potassium Carbonate → 6-Methoxy-2-(5-(methyl(2,2,6,6-tetramethylpiperidin-4-yl)amino)-1,3,4-thiadiazol-2-yl)-3,4-dihydroisoquinolin-1(2H)-one

Participants

Reaction Conditions

Reaction Steps

To a stirred suspension of 6-methoxy-3,4-dihydroisoquinolin-1(2H)-one (50 mg, 0.282 mmol) and 5-bromo-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)-1,3,4-thiadiazol-2-amine (Intermediate 4) (132 mg, 0.395 mmol) in DMF (0.7 mL) under nitrogen was added K2CO3 (78 mg, 0.564 mmol) followed by CuI (32 mg, 0.169 mmol). The reaction mixture was heated at 150° C. for ˜18 hours. A further 1.4 eq of 5-bromo-N-methyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)-1,3,4-thiadiazol-2-amine (132 mg, 0.395 mmol) and 0.6 eq of CuI (32 mg, 0.169 mmol) were added and stirring was continued at 150° C. for an additional 48 hours. The reaction mixture was diluted with EtOAc (10 mL) and filtered through celite. The filtrate was concentrated in vacuo to afford the crude product as a dark brown oil. The crude material was purified by UV directed preparative HPLC under acidic conditions (formic acid modified) collecting at 312 nm. The product containing fractions were combined and loaded onto a 2 g SCX cartridge (pre-wet with MeOH). The cartridge was washed with MeOH (˜20 mL) then flushed with 10% DCM in [7M NH3 in MeOH] (12 mL). The DCM/MeOH/NH3 was removed in vacuo to afford the title compound as a pale yellow/brown glass-like solid (28 mg, 23% yield). LC-MS: Rt 0.91 min; MS m/z 430.5 [M+H]+ [Method A]. 1H NMR (400 MHz, DMSO-d6) δ ppm 7.88-7.97 (m, 1H), 6.96-7.03 (m, 2H), 4.35 (t, J=6.57 Hz, 2H), 4.16 (tt, J=12.19, 3.22 Hz, 1H), 3.85 (s, 3H), 3.14 (t, J=6.57 Hz, 2H), 2.91 (s, 3H), 1.58 (dd, J=12.13, 3.03 Hz, 2H), 1.42 (t, J=11.87 Hz, 2H), 1.20 (s, 6H), 1.09 (s, 6H).

Provenance & Evidence