6-Bromo-2-tetralone → HCID 59486444, compound

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Reaction Steps

NH4OAc (10.19 g, 0.13 mol, 10 eq.) was added to a solution of 6-bromo-3,4-dihydronaphthalen-2(1H)-one (3 g, 0.13 mol, 1 eq.) in MeOH (100 ml) and the mixture was stirred for 2 h at RT. NaBH3CN (990 mg, 0.015 mol, 1.2 eq.) was added to the reaction mixture and it was stirred for another 16 h at RT. The reaction mixture was concentrated under reduced pressure, diluted with water (100 ml) and acidified with 1 N HCl solution. The mixture was extracted with DCM (2×100 ml) and the aqueous part basified with 1 N NaOH solution. Then the aqueous part was extracted with DCM (4×200 ml). The organic part was washed with brine (100 ml), dried over Na2SO4 and concentrated under reduced pressure. The reddish crude liquid thus obtained was used for the next step without further purification. Yield: 2.6 g 2. To a mixture of 6-bromo-1,2,3,4-tetrahydronaphthalen-2-amine (5.5 g, 24.3 mmol, 1 eq.) in DCM (120 ml) and TEA (10.24 ml, 72 mmol, 3 eq.) was added dropwise boc-anhydride (6 ml, 26 mmol, 1.1 eq.) at 0° C. and the mixture was then stirred at RT for 16 h. After completion of the reaction (monitored by TLC) the mixture was diluted with DCM (100 ml), the organic layer washed with water (100 ml) and brine (100 ml), and dried over anhydrous Na2SO4. The solvent was then evaporated to yield the desired compound as an off-white solid which was used in the next step without further purification. Yield: 7 g 3. BuLi (1.5 M, 15 ml, 22.5 mmol, 2 eq.) was added dropwise to a stirred solution of tert-butyl 6-bromo-1,2,3,4-tetrahydronaphthalen-2-ylcarbamate (3.5 g, 10.73 mmol, 1 eq.) in THF (100 ml) at −78° C. and the reaction mixture was stirred for 45 min at the same temperature. Then DMF (3 ml, 32.1 mmol, 3 eq.) was added to the reaction mixture very slowly at −78° C. and it was stirred for 1 h. After completion of the reaction (monitored by TLC) the mixture was quenched with saturated NH4Cl solution (20 ml) and diluted with ethyl acetate (100 ml). The organic part was separated, washed with water (100 ml) and brine (100 ml), and dried over Na2SO4. It was concentrated under reduced pressure to yield the crude product which was purified by column chromatography (silica gel, 20% EtOAc/hexanes) to give the desired compound as a yellowish liquid. Yield: 75% (2.2 g, 8 mmol) 4. A solution of t-BuNH2 (0.8 ml, 7.6 mmol, 1 eq.) in DCM (3 ml) was added to a solution of tert-butyl 6-formyl-1,2,3,4-tetrahydronaphthalen-2-ylcarbamate (2.1 g, 7.6 mmol, 1 eq.) in dry DCM (100 ml) at 0° C. and resulting reaction mixture was stirred at 25° C. for 2 h. The reaction mixture was cooled to 0° C., then NaBH3CN (4.45 g, 20.9 mmol, 3.0 eq.) was added portionwise and the mixture was then stirred at 25° C. for 16 h. The mixture was diluted with DCM (200 ml), washed with water (2×50 ml) and brine (2×50 ml) and the organics were dried over Na2SO4. The solvent was evaporated under reduced pressure and the residue purified by column chromatography (silica gel; 5% EtOAc/hexanes) to yield the desired product as a white solid. Yield: 72% (1.8 g, 5.4 mmol) 5. TFA (14 ml, 0.192 mol, 40 eq.) was added to a solution of tert-butyl 6-((tert-butylamino)methyl)-1,2,3,4-tetrahydronaphthalen-2-ylcarbamate (1.6 g, 4.8 mmol, 1.0 eq.) in DCM (100 ml) at 0° C. and resulting reaction mixture was stirred at 25° C. for 30 min. The solvent was evaporated under reduced pressure and the residue obtained was diluted with EtOH (50 ml). The mixture was basified with Amberlyst (A-21, ˜6 g) to pH 9-10 and then stirred for 1 h. The reaction mixture was filtered and concentrated under reduced pressure to give a yellowish solid which was used for the next step without further purification. Yield: quantitative

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