19731-71-6Relevant articles and documents
Metal-free, redox-neutral, site-selective access to heteroarylamine via direct radical?radical cross-coupling powered by visible light photocatalysis
Zhou, Chao,Lei, Tao,Wei, Xiang-Zhu,Ye, Chen,Liu, Zan,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
supporting information, p. 16805 - 16813 (2020/11/09)
Transition-metal-catalyzed C?N bond-forming reactions have emerged as fundamental and powerful tools to construct arylamines, a common structure found in drug agents, natural products, and fine chemicals. Reported herein is an alternative access to heteroarylamine via radical?radical cross-coupling pathway, powered by visible light catalysis without any aid of external oxidant and reductant. Only by visible light irradiation of a photocatalyst, such as a metal-free photocatalyst, does the cascade single-electron transfer event for amines and heteroaryl nitriles occur, demonstrated by steady-state and transient spectroscopic studies, resulting in an amine radical cation and aryl radical anion in situ for C?N bond formation. The metal-free and redox economic nature, high efficiency, and site-selectivity of C?N cross-coupling of a range of available amines, hydroxylamines, and hydrazines with heteroaryl nitriles make this protocol promising in both academic and industrial settings.
Thermal decomposition of O-benzyl ketoximes; role of reverse radical disproportionation
Blake, Jessie A.,Ingold, Keith U.,Lin, Shuqiong,Mulder, Peter,Pratt, Derek A.,Sheeller, Brad,Walton, John C.
, p. 415 - 420 (2007/10/03)
Thermolyses of seven dialkyl, two alkyl-aryl and two diaryl O-benzyl ketoxime ethers, R1R2C=NOCH2Ph, have been examined in three hydrogen donor solvents: tetralin, 9,10-dihydrophenanthrene, and 9,10-dihydroanthracene. All the oxime ethers gave the products expected from homolytic scission of both the O-C bond (viz., R1R2C=NOH and PhCH3) and N-O bond (viz., R1R2C=NH and PhCH2OH). The yields of these products depended on which solvent was used and the rates of decomposition of the O-benzyl oxime ethers were greater in 9,10-dihydrophenanthrene and 9,10-dihydroanthracene than in tetralin. These results indicated that a reverse radical disproportionation reaction in which a hydrogen atom was transferred from the solvent to the oxime ether, followed by β-scission of the resultant aminoalkyl radical, must be important in the latter two solvents. Benzaldehyde was found to be an additional product from thermolyses conducted in tetralin. This, and other evidence, indicated that another induced decomposition mode involving abstraction of a benzylic hydrogen atom, followed by β-scission of the resulting benzyl radical, became important for some substrates. Participation by minor amounts of enamine tautomers of the oxime ethers was shown to be negligible by comparison of thermolysis data for the O-benzyloxime of bicyclo[3.3.1]nonan-9-one, which cannot give an enamine tautomer, with that of the O-benzyloxime of cyclohexanone.
Preparation of six membered carocycles by aryl-tellurium mediated free-radical cyclisation
Barton,Dalko,Gero
, p. 4713 - 4716 (2007/10/02)
Radical cyclisation of various telluro-compounds was examined. Olefins conjugated to an electron withdrawing group, (7, 8, 9, 10, and 11) gave high yields of the corresponding six membered products. Non-activating olefin 23 gave the corresponding thiopyridyl derivative 24 as the only product. The photolysis, using oxime 18 as radicophile for the cyclisation, proceeded slowly at room temperature, and gave only a low yield of products 19 and 20.
