19358-40-8Relevant articles and documents
Dehydrogenative and Redox-Neutral N-Heterocyclization of Aminoalcohols Catalyzed by Manganese Pincer Complexes
Brzozowska, Aleksandra,Rueping, Magnus,Sklyaruk, Jan,Zubar, Viktoriia
supporting information, (2022/03/17)
A new manganese catalyzed heterocyclization of aminoalcohols has been accomplished. A wide range of heterocycles were synthesized, including 1,2,3,4-tetrahydroquinolines, dihydroquinolinones, and 2,3,4,5-tetrahydro-1H-benzo[b]azepines. The reaction is performed under mild reaction conditions using air and moisture stable manganese catalysts. The desired heterocycles were obtained in good to excellent yields.
Visible-Light Induced C(sp2)?H Amidation with an Aryl–Alkyl σ-Bond Relocation via Redox-Neutral Radical–Polar Crossover
Chang, Sukbok,Jeong, Jiwoo,Jung, Hoimin,Keum, Hyeyun,Kim, Dongwook
supporting information, p. 25235 - 25240 (2021/10/25)
We report an approach for the intramolecular C(sp2)?H amidation of N-acyloxyamides under photoredox conditions to produce δ-benzolactams with an aryl-alkyl σ-bond relocation. Computational studies on the designed reductive single electron transfer strategy led us to identify N-[3,5-bis(trifluoromethyl)benzoyl] group as the most effective amidyl radical precursor. Upon the formation of an azaspirocyclic radical intermediate by the selective ipso-addition with outcompeting an ortho-attack, radical–polar crossover was then rationalized to lead to the rearomative ring-expansion with preferential C?C bond migration.
Stereoelectronic and Resonance Effects on the Rate of Ring Opening of N-Cyclopropyl-Based Single Electron Transfer Probes
Grimm, Michelle L.,Suleman, N. Kamrudin,Hancock, Amber N.,Spencer, Jared N.,Dudding, Travis,Rowshanpour, Rozhin,Castagnoli, Neal,Tanko, James M.
supporting information, p. 2640 - 2652 (2020/02/18)
N-Cyclopropyl-N-methylaniline (5) is a poor probe for single electron transfer (SET) because the corresponding radical cation undergoes cyclopropane ring opening with a rate constant of only 4.1 × 104 s-1, too slow to compete with other processes such as radical cation deprotonation. The sluggish rate of ring opening can be attributed to either (i) a resonance effect in which the spin and charge of the radical cation in the ring-closed form is delocalized into the phenyl ring, and/or (ii) the lowest energy conformation of the SET product (5a￠+) does not meet the stereoelectronic requirements for cyclopropane ring opening. To resolve this issue, a new series of N-cyclopropylanilines were designed to lock the cyclopropyl group into the required bisected conformation for ring opening. The results reveal that the rate constant for ring opening of radical cations derived from 1′-methyl-3′,4′-dihydro-1′H-spiro[cyclopropane-1,2′-quinoline] (6) and 6′-chloro-1′-methyl-3′,4′-dihydro-1′H-spiro[cyclopropane-1,2′-quinoline] (7) are 3.5 × 102 s-1 and 4.1 × 102 s-1, effectively ruling out the stereoelectronic argument. In contrast, the radical cation derived from 4-chloro-N-methyl-N-(2-phenylcyclopropyl)aniline (8) undergoes cyclopropane ring opening with a rate constant of 1.7 × 108 s-1, demonstrating that loss of the resonance energy associated with the ring-closed form of these N-cyclopropylanilines can be amply compensated by incorporation of a radical-stabilizing phenyl substituent on the cyclopropyl group. Product studies were performed, including a unique application of EC-ESI/MS (Electrochemistry/ElectroSpray Ionization Mass Spectrometry) in the presence of 18O2 and H218O to elucidate the mechanism of ring opening of 7a￠+ and trapping of the resulting distonic radical cation.
