Visible-Light-Induced Photoaddition of N-Nitrosoalkylamines to Alkenes: One-Pot Tandem Approach to 1,2-Diamination of Alkenes from Secondary Amines

Abstract

The generation of aminium radical cation species from N-nitrosoamines is disclosed for the first time through visible-light excitation at 453 nm. The developed visible-light-promoted photoaddition reaction of N-nitrosoamines to alkenes was combined with the o-NQ-catalyzed aerobic oxidation protocol of amines to telescope the direct handling of harmful N-nitroso compounds, where the desired α-amino oxime derivatives were obtained in a one-pot tandem N-nitrosation and photoaddition sequence.

Bioinspired o-Naphthoquinone-Catalyzed Aerobic Oxidation of Alcohols to Aldehydes and Ketones

“…The substituted naphthalene-1,2-diols are a redox-active chemical species under aerobic conditions, readily generating ortho -naphthoquinones ( o -NQs) with thermal and chemical stability . To capitalize on the redox process of o -NQs, the aerobic oxidations of amines to imines, aldehydes and ketones, N-nitrosoamines, and carboxylic acids have been explored. Given that the o -NQ catalysts are compatible under both acidic and basic conditions, Ito and Fukuzumi’s biomimetic ADH activity via the hemiacetal mechanistic proposal was explored with the o -NQ catalyst system.…”

Visible-Light-Promoted Photoaddition of N-Nitrosopiperidines to Alkynes: Continuous Flow Chemistry Approach to Tetrahydroimidazo[1,2-a]pyridine 1-Oxides

“…The long-standing notion for the photochemical reaction of N -nitrosamines was homolytic N–NO bond cleavage to obtain the aminium radical cation and nitric oxide radical (Scheme a) . In contrast to the conventional photochemical N–NO bond cleavage of N -nitrosamines, which targeted the singlet excited-state energy transitions at 230 nm for the S 0 → S 2 (π N → π* NO ) transition and 360 nm for the S 0 → S 1 (n N → π* NO ) transition, the visible-light excitation of the S 0 → T 1 (π O → π* NO ) transition at 453 nm can effect the homolytic cleavage of N -nitrosamines (Scheme b) . Targeting the triplet excited-state energy transition under visible-light irradiation eliminates the use of conventional photochemical reaction setups that typically necessitated an external cooling immersion-well reactor equipped with a Hanovia UV lamp through a Vycor filter …”

“…The current visible-light-promoted photoaddition of N -nitrosamines to alkynes relies on the generation of the aminium radical cation from the direct excitation of the protonated N -nitrosamine via the S 0 → T 1 (π O → π* NO ) transition . Accordingly, the visible lights with a wavelength of 400 nm were expected to induce the homolytic N–NO bond cleavage through the S 0 → T 1 (π O → π* NO ) transition at 450 nm.…”

“…4 In contrast to the conventional photochemical N−NO bond cleavage of Nnitrosamines, which targeted the singlet excited-state energy transitions at 230 nm for the S 0 → S 2 (π N → π* NO ) transition and 360 nm for the S 0 → S 1 (n N → π* NO ) transition, 5 the visiblelight excitation of the S 0 → T 1 (π O → π* NO ) transition at 453 nm can effect the homolytic cleavage of N-nitrosamines (Scheme 1b). 6 Targeting the triplet excited-state energy transition under visible-light irradiation eliminates the use of conventional photochemical reaction setups that typically necessitated an external cooling immersion-well reactor equipped with a Hanovia UV lamp through a Vycor filter. 7 The photochemical addition of N-nitrosamines to alkenes allows a facile 1,2-diamination of alkenes to provide the α-amino oxime derivatives.…”

“…17 The current visible-light-promoted photoaddition of Nnitrosamines to alkynes relies on the generation of the aminium radical cation from the direct excitation of the protonated Nnitrosamine via the S 0 → T 1 (π O → π* NO ) transition. 6 Accordingly, the visible lights with a wavelength of 400 nm were expected to induce the homolytic N−NO bond cleavage through the S 0 → T 1 (π O → π* NO ) transition at 450 nm. Thus, a plausible reaction mechanism for tetrahydroimidazo [1,2-a]pyridine 1-oxides under the visible-light conditions is proposed on the basis of the photochemical decomposition of the N−NO bond to give the aminium radical cation and nitric oxide radical (Scheme 4a).…”