Carbon tetrabromide → tert-Butyl N-[3-(bromomethyl)benzyl]-N-methylcarbamate

Participants

Reaction Steps

A milky suspension of 3-[(methylamino)methyl]phenylmethanol (preparation 12) (2.7 g, 17.9 mmol) in THF (60 ml) and water (60 ml) was treated with di-t-butylpyrocarbonate (5.4 g,24.7 mmol) and the mixture stirred at room temperature overnight. The THF was evaporated and the aqueous residue treated with ethyl acetate (250 ml). The organic layer was washed with sat aq brine (100 ml) a and dried over MgSO4. Filtration away from the drying agent followed by evaporation of the solvent gave the crude product which was purified by chromatography (SiO2, eluting with 95:5CH2Cl2:MeOH) to give the intermediate tert-butyl N-[3-(hydroxymethyl)benzyl]-N-methylcarbamate(4.2 g) which was used directly in the next step. A stirred solution of tert-butyl-N-[3-(hydroxymethyl)benzyl]-N-methylcarbamate (4.2 g, 16.7 mmol) in CH2Cl2 (150 ml) at 0° C., was treated with carbon tetrabromide (8.0 g, 24.1 mmol) and triphenyl phosphine (6.35 g, 24.21 mmol). The resultant solution was warmed to room temperature and stirred for 4 days. The resultant mixture was evaporated to dryness and the residue purified by chromatography (SiO2, gradient elution with 100% hexane; 99:1 hexane:ethyl acetate; 95:5 hexane:ethyl acetate) to give the desired product (3.32 g, 60%). 1H NMR (CDCl3) δ 1.50 (s, 9H), 2.80 (s, br, 3H), 4.20 (s, 2H), 4.30 (s, 2H), 7.15 (m, 1H), 7.25 (m, 1H), 7.30 (m, 2H). LRMS m/z=333.2 (M+18)+.

Provenance & Evidence