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Abstract

Primary and secondary amines can be rapidly and quantitatively oxidized to the corresponding imines by singlet oxygen. This reactive form of oxygen was produced using a variable-temperature continuous-flow LED-photoreactor with a catalytic amount of tetraphenylporphyrin as the sensitizer. -Aminonitriles were obtained in good to excellent yields when trimethylsilyl cyanide served as an insitu imine trap. At 25°C, primary amines were found to undergo oxidative coupling prior to cyanide addition and yielded secondary -aminonitriles. Primary -aminonitriles were synthesized from the corresponding primary amines for the first time, by an oxidative Strecker reaction at -50 degrees C. This atom-economic and protecting-group-free pathway provides a route to racemic amino acids, which was exemplified by the synthesis of tert-leucine hydrochloride from neopentylamine.