Cyclopentadiene → 5-Nitro-1,4-dihydro-1,4-methanonaphthalene

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Reaction Steps

In a three necked flask equipped with thermometer, dropping funnel and cooler with a bubbler, tertio-butyl nitrite (5.77 ml, 1.77 eq, 48.6 mmol) is dissolved in dichloromethane (30 ml) and heated to reflux while a solution of cold 2-amino-6-nitro-benzoic acid (5 g, 1 eq, 27.5 mmol) and cyclopentadiene (40.7 ml, 18 eq, 0.49 mol) in acetone (20 ml) is added dropwise. Care should be taken regarding gas evolution. After refluxing for 18 hours, the reaction is cooled down to ambient temperature before being filtrated through a silica pad and evaporated. The crude mixture is purified by chromatography column (silica gel, elution with a gradient from pure cyclohexane to a mixture of ethyl acetate:cyclohexane 1:12. 3 grams of 5-nitro-1,4-dihydro-1,4-methano-naphthalene are then obtained (58% yield). 1H NMR (CDCl3) 7.7 ppm, 1H, dd, J=0.7 and 8.4 Hz; 7.45 ppm, 1H, dt, J=7.3 and 0.7 Hz; 7.07 ppm, 1H, dd, J=7.3 and 8.4 Hz; 6.9-6.86 ppm, 2H, m; 4.86 ppm, 1H, bs; 4.02 ppm, 1H, bs; 2.38 ppm, 1H, dt, J=7.7 and 1.5 Hz; 2.3 ppm, 1H, dt, J=7.4 and 1.5 Hz.

Provenance & Evidence