title: Continuous-flow oxidative cyanation of primary and secondary amines using singlet oxygen.
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. α-Aminonitriles were obtained in good to excellent yields when trimethylsilyl cyanide served as an in situ imine trap. At 25°C, primary amines were found to undergo oxidative coupling prior to cyanide addition and yielded secondary α-aminonitriles. Primary α-aminonitriles were synthesized from the corresponding primary amines for the first time, by an oxidative Strecker reaction at -50 °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.
authors.affiliation: Department für Biomolekulare Systeme, Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Am Mühlenberg 1, 14476 Potsdam (Germany).
authors.forename: Dmitry B
authors.initials: DB
authors.lastname: Ushakov
authors.forename: Kerry
authors.initials: K
authors.lastname: Gilmore
authors.forename: Daniel
authors.initials: D
authors.lastname: Kopetzki
authors.forename: D Tyler
authors.initials: DT
authors.lastname: McQuade
authors.forename: Peter H
authors.initials: PH
authors.lastname: Seeberger
mesh_terms: D000588:Amines / Q000737:chemistry*; D003486:Cyanides / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D015394:Molecular Structure; D009570:Nitriles / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D010777:Photochemistry; D011166:Porphyrins / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry*
chemical_list: D000588:Amines; D003486:Cyanides; D007097:Imines; D009570:Nitriles; D011166:Porphyrins; C409084:tetraphenylporphyrin; D026082:Singlet Oxygen
keywords: CH activation; Strecker reaction; amines; flow chemistry; photooxidation