Sulfuric Acid → 9-Methyl-3,9-diazabicyclo(4.2.1)nonan-4-one

Participants

Reaction Conditions

Reaction Steps

9-Methyl-3,9-diazabicyclo[4.2.1]nonane (J. Org. Chem., 1960, 637 ). Conc. H2SO4 (6.25 ml, 0.117 mol) was added dropwise to a stirred cold (−5° C.) solution of 8-methyl-8-azabicyclo[3.2.1]octan-3-one (2.78 g, 0.02 mol) in CHCl3(25 ml) while keeping the temperature below 15° C. After cooling to 0-5° C., neat sodium azide (2.60 g, 0.040 mol) was added in small portions while maintaining pot temperature below 35° C. The mixture stirred at rt for 2 h and then heated at 50° C. for 2 h. Rxn mixture was poured into ice and neutralized with Na2CO3 and then basify with 50% NaOH. Organic layer separated and the aq. layer re-extracted with CHCl3 (2×25 ml). Combined organic layers were washed with water (10 ml), brine and dried (MgSO4). Evaporation of CHCl3 gave 9-methyl-3,9-diazabicyclo[4.2.1]nonan-4-one as a off-white solid (1.15 g, 37%). 1H NMR (400 MHz, CHLOROFORM-D) ppm 1.67-1.75 (m, 1H) 1.77-1.85 (m, 1H) 2.05-2.16 (m, 2H) 2.42 (s, 3H) 2.46 (ddd, J=16.05, 6.23, 2.14 Hz, 1H) 2.80-2.90 (m, 2H) 3.17 (t, J=6.42 Hz, 1H) 3.24 (t, J=6.30 Hz, 1H) 3.60 d), J=14.60 Hz, 1H) 5.90 (s, 1H).

Provenance & Evidence