Ammonia → 6,7-Dimethoxy-1,2,3,4-tetrahydronaphthalen-1-amine hydrochloride

Temperature

0 °C

3,4-Dihydro-6,7-dimethoxynaphthalen-1(2H)-one (5.00 g, 24.2 mmol), titanium(IV) isopropoxide (14.1 mL, 48.5 mmol) and 2 M solution of ammonia in ethanol (60.6 mL, 121 mmol) were stirred at room temperature for 6 h. The reaction was cooled to 0° C. and sodium borohydride was added portionwise during 10 min (1.37 g, 36.4 mmol); the resultant mixture was stirred at rt for an additional 3 h. The reaction was quenched by pouring it into ammonium hydroxide (2 M, 130 mL), the precipitate that formed was filtered off and washed with ethyl acetate (25 mL×3). The organic layer was separated and the remaining aqueous layer was extracted with ethyl acetate (25 mL×2). The combined organic extracts were washed with 1 M HCl (50 mL). The acidic aqueous extracts were washed with ethyl acetate (100 mL), then treated with aqueous sodium hydroxide (2 M) to pH 10-12, and extracted with ethyl acetate (75 mL×3). The combined organic extracts were washed with brine (75 mL), dried (Na2SO4), and concentrated in vacuo to afford the desired product (200 mg, 4% yield). 1H NMR (400 MHz, CDCl3): δ 6.95 (s, 1H), 6.56 (s, 1H), 3.92 (m, 1H), 3.88 (s, 3H), 3.85 (s, 3H), 2.71 (m, 2H), 1.97 (m, 2H), 1.76 (m, 2H).

1. customThe reaction was quenched
2. additionby pouring it into ammonium hydroxide (2 M, 130 mL)
3. customthe precipitate that formed
4. filtrationwas filtered off
5. washwashed with ethyl acetate (25 mL×3)
6. customThe organic layer was separated
7. extractionthe remaining aqueous layer was extracted with ethyl acetate (25 mL×2)
8. washThe combined organic extracts were washed with 1 M HCl (50 mL)
9. washThe acidic aqueous extracts were washed with ethyl acetate (100 mL)
10. additiontreated with aqueous sodium hydroxide (2 M) to pH 10-12
11. extractionextracted with ethyl acetate (75 mL×3)
12. washThe combined organic extracts were washed with brine (75 mL)
13. dry with materialdried (Na2SO4)
14. concentrationconcentrated in vacuo

ORD record

ord-a1554acc1be544f9b7deddd378d9c328

Source dataset

uspto-grants-2013_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08604021B2