2-Aminobenzyl alcohol → 4H-3,1-Benzothiazin-2-amine

2-aminobenzylalcohol (2.0 g, 16 mmol) in conc. HCl (10 ml) is heated at 100° C. for 15 minutes in a sealed vial, the resulting precipitate is filtered, washed with diethyl ether to give a white solid which is dissolved in isopropanol (20 ml) and treated with thiourea. The resulting reaction mixture is refluxed for 20 hours then concentrated, and the residue taken up with H2O and basified with 2 N NaOH. The basic solution thus obtained is extracted with CH2Cl2. The organic extracts are combined, washed with H2O, dried over Na2SO4 and then concentrated. The residue is purified by chromatography through silica, eluting with petroleum ether/AcOEt (1:1), and then recrystallised from EtOH to give the desired product as a pale yellow solid, m.p. 132-135° C., with a yield of 64%. 1H-NMR (CDCl3): 3.90 (s, 2H), 5.09 (br s, 2H), 7.00-7.12 (m, 3H) 7.20-7.28 (m, 1H). 165 (M+H+). The compound is more stable as the oxalate salt, m.p. 178-182° C., prepared by precipitation with oxalic acid.

1. filtrationis filtered
2. washwashed with diethyl ether
3. customto give a white solid which
4. customThe resulting reaction mixture
5. temperatureis refluxed for 20 hours
6. concentrationthen concentrated
7. customThe basic solution thus obtained
8. extractionis extracted with CH2Cl2
9. washwashed with H2O
10. dry with materialdried over Na2SO4
11. concentrationconcentrated
12. customThe residue is purified by chromatography through silica
13. washeluting with petroleum ether/AcOEt (1:1)
14. customrecrystallised from EtOH

ORD record

ord-013735b4074e4023b7276b2822bc2295

Source dataset

uspto-grants-2013_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08420634B2