Ammonium Hydroxide → Racemic-trans-4-amino-6-bromochroman-3-ol

HRID 1516333Notes

Reaction equation

Br[C@H:2]1[C@H:11](O)[C:10]2[C:5](=[CH:6][CH:7]=[C:8]([Br:13])[CH:9]=2)[O:4][CH2:3]1.[OH-:14].[NH4+:15]>C(O)(C)C>[NH2:15][C@@H:11]1[C:10]2[C:5](=[CH:6][CH:7]=[C:8]([Br:13])[CH:9]=2)[O:4][CH2:3][C@H:2]1[OH:14]

Participants

Conditions

Temperature: 2.5 °C

Procedure

To a solution of racemic-trans-3,6-dibromochroman-4-ol (30.0 g, 97.4 mmol) in isopropyl alcohol (300 mL) at ambient temperature (500 mL), add ammonium hydroxide (28-30% aq., 150 mL, 2.2 mol). Stir slowly for 15 hr. Filter the reaction mixture and dilute the filtrate with water (200 mL). Concentrate the resulting solution under reduced pressure to one half of its original weight. Add water (100 mL), stir the mixture at ambient temperature for 10 min., then cool to 0-5° C. and stir for an additional 30 min. Collect the precipitate by filtration and wash the solids with water (25 mL) and heptanes (25 mL). Vacuum dry the material at 40° C. to afford the title compound as a pale yellow solid (21.2 g, 89.2%). 1H NMR (DMSO-d6) δ 1.96 (bs, 2H), 3.53 (m, 2H), 3.87 (dd, 1H), 4.11 (dd, 1H), 5.15 (bs, 1H), 6.66 (d, 1H), 7.19 (dd, 1H), 7.48 (dd, 1H). LC-ES/MS m/z (79Br) 244 [M+H].

Workup

filtrationFilter the reaction mixture
additiondilute the filtrate with water (200 mL)
concentrationConcentrate the resulting solution under reduced pressure to one half of its original weight
stirringAdd water (100 mL), stir the mixture at ambient temperature for 10 min.
stirringstir for an additional 30 min
customCollect the precipitate
filtrationby filtration
washwash the solids with water (25 mL) and heptanes (25 mL)
customVacuum dry the material at 40° C.

Sources & evidence

ORD record: ord-0515212dd24749af8260d0536a94e74c
Source dataset: uspto-grants-2012_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08227468B2

Reaction notes

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