2,5-Dimethylpyridine → 6,7-Dihydro-5H-cyclopenta[b]pyridine 1-oxide

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Reaction Conditions

Reaction Steps

N-Oxide Formation. 5 g of 2,5-dimethyl-pyridine and 8.8 g urea-hydrogen peroxide adduct were heated together to 85° C. The mixture melted and was stirred for 18 h at 85° C. It was then cooled to rt and taken up in water-EtOAc and layers separated. The product containing aqueous layer was treated with solid NaCl and concentrated under reduced pressure and back-extracted several times with EtOAc. The back-extracted organic solution was concentrated and the product crystallized. Three crops were collected by filtration for a total of 3.73 g 2,5-dimethyl-pyridine 1-oxide. LCMS (m/z) 124. N-oxide formation also was performed under the following conditions. To a 6,7-dihydro-5H-[1]pyrindine solution in DCM at 0° C. was added peracetic acid (3 mL, 32% in AcOH), and the reaction was slowly allowed to come to rt and stirred for 12 h. The reaction mixture was diluted with DCM (5 mL) and washed with water, aq NaHCO3, brine, then dried over Na2SO4, filtered and concentrated to afford desired 6,7-dihydro-5H-[1]pyrindine 1-oxide (0.6 g). LCMS (m/z): 136.

Provenance & Evidence