Hydrochloric Acid → HCID 54135301, compound

Participants

Reaction Steps

Schiff base (6) (97.1 g, 0.4M) is dissolved in THF (250 ml) and shaken in a separatory funnel with 10% aqueous HCl (1 l) for 5 minutes. This mixture is washed with Et2O (3×250 ml), the aqueous phase separated, neutralized with solid NaHCO3 and extracted with CHCl3 (3×250 ml). The combined CHCl3 extracts are dried over anhydrous MgSO4, filtered and evaporated to yield a pale yellow liquid, 57.9 g (93% yield). 'H-N.M.R. (CDCl3 /TMS): δ=1.30 (t, 3H, --CH2CH3); 1.50 (s, 2H, --NH2); 1.47-2.38 (m, 4H, --CH2CH2 --); 3.43 (dd, 1H, >CH--CH2 --, J=6 and 8 Hz); 4.20 (q, 2H, --CH2CH3); 4.80-5.20 (m, 2H, --CH=CH2); 5.45-6.20 ppm (m, 1H, --CH=CH2). The latter is stirred in CH2Cl2 (600 ml) containing Et3N (51 ml, 0.37M) and cooled in an ice bath before benzoyl chloride (43 ml, 0.37M) in CH2Cl2 (100 ml) is added dropwise over a period of 1/2 hour. The reaction mixture is allowed to warm to room temperature and stirred overnight. The formed Et3N HCl is removed by filtration and the filtrate is evaporated to dryness. The residue is taken up in Et2O, filtered, washed with 5% aqueous HCl (3×100 ml), saturated aqueous NaHCO3 (3×100 ml), saturated aqueous NaCl (3×100 ml), dried over anhydrous MgSO4 and evaporated to dryness. The white solid thus obtained is recrystallized twice from Et2O/hexane to yield 64.3 g of the desired product (7) (67% yield) m.p. 68°-70° C. The two recrystallizations are required in order to remove an impurity which turned out to be the bis alkylated material (m.p. 46°-49° C.) that is carried along. 'H-N.M.R. (CDCl3 /TMS): δ=1.3 (t, 3H, --CH2CH3); 1.80-2.34 (m, 4H, --CH2CH2 --); 4.28 (q, 2H, --CH2CH3); 4.64-5.15 (m, 3H, >CH=CH2 and CHCO2Et); 5.53-6.0 (m, 1H, CHCH2); 6.70 (d, 1H, >NH); 7.30-7.85 ppm (m, 5H, Ph).

Provenance & Evidence