Hydrochloric Acid → (-)-(4R)-4-(3-thienylmethyl)-4,5-dihydro-1,3-thiazol-2-ylamine hydrochloride

Participants

Reaction Conditions

Reaction Steps

A mixture of 0.94 g of N-(tert-butyl)-N′-[(1R)-2-hydroxy-1-(3-thienylmethyl)ethyl]thiourea in 9.2 cm3 of 6N hydrochloric acid is heated at a temperature in the region of 100° C. with stirring for 3 hours and is then concentrated under reduced pressure (2 kPa) at a temperature in the region of 40° C. A greenish oil is obtained, which is taken up in 10 cm3 of acetone to give a sticky gum. 1.5 cm3 of ethanol are then added, followed by dropwise addition, with stirring, of 6 cm3 of diethyl ether. The crystals obtained are filtered off on a sinter funnel, washed with diethyl ether and then dried in an oven under vacuum (10 Pa) at a temperature in the region of 50° C. 0.5 g of (−)-(4R)-4-(3-thienylmethyl)-4,5-dihydro-1,3-thiazol-2-ylamine hydrochloride is obtained in the form of gray crystals melting at 152° C. 1H NMR spectrum (400 MHz, (CD3)2SO-d6, δ in ppm): 2.99 (mt: 2H); 3.26 (dd, J=11 and 5.5 Hz: 1H); 3.59 (dd, J=11 and 8 Hz: 1H); 4.54 (mt: 1H); 7.10 (dd, J=5.5 and 1 Hz 1H); 7.38 (mt: 1H); 7.54 (dd, J=5 and 3 Hz: 1H); from 9.15 to 10.55 (broad unres. mult.: 3H). (αD20=−4.3±0.5 at a concentration of 0.5% in methanol).

Provenance & Evidence