Hydrochloric Acid → 5-(4-Methyl-piperazin-1-ylmethyl)-1,3-dihydro-isoindole-2-carboxylic acid benzyl ester dihydrochloride salt

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Reaction Conditions

Reaction Steps

The solid from Step 3 (assume 0.232 mol) was dissolved in acetone (700 mL) and this solution was added over 45 mins to a cooled (internal temp 15-17° C.) suspension of K2CO3 (48 g) and N-methylpiperazine (50 mL, 0.45 mol) in acetone (330 mL). The suspension was stirred at 15° C. for 3 h (complete removal of starting material by tlc) when the solution was evaporated to a small volume and the residue partition between EtOAc (1000 mL) and a mixture of water (500 mL) and saturated brine (50 mL). The organic phase was washed with a mixture of water (500 mL) and saturated brine (150 mL) and finally washed with saturated brine (300 mL). The solution was dried (MgSO4) and filtered and to this solution was added 1M-HCl in MeOH (430 mL, 0.43 mol). The suspension was cooled (0° C. for 30 mins) and the solid removed by filtration which was washed with EtOAc and then heptane on the sinter and the solid dried (oil-pump, RT 72 h) to give crop 1 of the title compound 66.34 g (65%) as a colourless solid. 1H NMR (400 MHz, Me-d3-OD): 7.64-7.51 (m, 2H), 7.51-7.29 (m, 6H), 5.23 (s, 2H), 4.79 (dd, J=16.2, 6.1 Hz, 4H), 4.49 (s, 2H), 3.66 (s, 8H), 3.03 (s, 3H).

Provenance & Evidence