Diisopropyl Ether → 1-(3,4-dihydro-2H-1-benzopyran-2-yl)methanamine

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Reaction Steps

A mixture of 2-chlorocarbonyl-3,4-dihydro-2H-1-benzopyran (0.47 mol) in N,N-dimethylacetamide (100 ml), a solution of thiophene (4%) (3 ml) and 2,2'-oxybispropane (400 ml) was hydrogenated with palladium on activated carbon (10%) (5 g) as a catalyst. After uptake of hydrogen (1 eq.), the catalyst was filtered off and the filtrate was evaporated. The residue, potassium acetate (20 g) and benzenemethanamine (50 g) in N,N-dimethylacetamide (2 ml) and methanol (300 ml) was hydrogenated with palladium on activated carbon (10%) (5 g) as a catalyst. After uptake of hydrogen (1 eq.), the catalyst was filtered off and the filtrate was evaporated. The residue in methanol (500 ml) was hydrogenated with palladium on activated carbon (10%) (5 g) as a catalyst. After uptake of hydrogen (1 eq.), the catalyst was filtered off and the filtrate was evaporated. The residue was taken up in 1,1'-oxybisethane and washed with a NaOH-solution. The organic layer was dried (MgSO4), filtered off and evaporated. The residue (70 g) was distilled at 70° C. (0.1 mm Hg), yielding 48.7 g (63.5%) of (±)-3,4-dihydro-2H-1-benzopyran-2-methanamine (interm. 15-c).

Provenance & Evidence