Functional-group-transfer strategies that avoid the use of unsustainable chemicals are attractive for the development of green methodologies.Chlorofluorocarbons(CFCs)not only contribute to the depletion of the stratos...Functional-group-transfer strategies that avoid the use of unsustainable chemicals are attractive for the development of green methodologies.Chlorofluorocarbons(CFCs)not only contribute to the depletion of the stratospheric ozone layer,but their gaseous nature also poses a serious threat in scientific laboratories.Hence,the design of effective and sustainable alternatives to CFCs is highly desirable.Herein,a practical CFC transfer platform for the addition of both a fluoroalkyl group and a chlorine substituent across alkenes by a photomediated redox-neutral manifold using bench-stable and easy-to-handle oxime-based surrogates is reported.The distinct reactivity of these tunable reagents allows for their single-electron reduction to trigger fragmentation driven by benzonitrile formation and loss of carbon dioxide.The other fragments released in that step,namely an electrophilic fluoroalkyl radical and a nucleophilic chloride anion,are subsequently transferred onto alkenes by a radical-ionic mechanism to deliver the desired chlorofluorocarbon products.展开更多
Ozone (O3) is a stratospheric layer that plays important role in providing support to humans for their survival. It is an essential factor for many global, biological and environmental phenomena. The ultra-violet (UV)...Ozone (O3) is a stratospheric layer that plays important role in providing support to humans for their survival. It is an essential factor for many global, biological and environmental phenomena. The ultra-violet (UV) rays emitted from sun are captured by ozone and thereby provide a stable ontological structure in the biosphere. Various anthropogenic activities such as emissions of CFCs, HCFCs and other organo-halogens lead to the depletion of ozone. The ozone depletion resulted in secondary production of an ozone layer near the ground (terrestrial ozone layer), which is responsible for adverse effects on plants, humans and environment with increased number of bronchial diseases in humans. The mutations caused by UV rays result in variation in morphogenic traits of plants which ultimately decreases crop productivity. However, UV radiation is required in optimum intensity for both plants and animals. This review takes into an account the wide ranging effects of ozone depletion with a majority of them being detrimental to the plant system.展开更多
基金by the Alexander von Humboldt Foundation(postdoctoral fellowship to M.Z.,2021-2023)in part by the Deutsche Forschungsgemeinschaft(grant no.Oe 249/26-1)is gratefully acknowledged+1 种基金M.Z.is also grateful for financial support from the University of Science and Technology of China(grant no.KY9990000197)M.O.is indebted to the Einstein Foundation Berlin for an endowed professorship.
文摘Functional-group-transfer strategies that avoid the use of unsustainable chemicals are attractive for the development of green methodologies.Chlorofluorocarbons(CFCs)not only contribute to the depletion of the stratospheric ozone layer,but their gaseous nature also poses a serious threat in scientific laboratories.Hence,the design of effective and sustainable alternatives to CFCs is highly desirable.Herein,a practical CFC transfer platform for the addition of both a fluoroalkyl group and a chlorine substituent across alkenes by a photomediated redox-neutral manifold using bench-stable and easy-to-handle oxime-based surrogates is reported.The distinct reactivity of these tunable reagents allows for their single-electron reduction to trigger fragmentation driven by benzonitrile formation and loss of carbon dioxide.The other fragments released in that step,namely an electrophilic fluoroalkyl radical and a nucleophilic chloride anion,are subsequently transferred onto alkenes by a radical-ionic mechanism to deliver the desired chlorofluorocarbon products.
文摘Ozone (O3) is a stratospheric layer that plays important role in providing support to humans for their survival. It is an essential factor for many global, biological and environmental phenomena. The ultra-violet (UV) rays emitted from sun are captured by ozone and thereby provide a stable ontological structure in the biosphere. Various anthropogenic activities such as emissions of CFCs, HCFCs and other organo-halogens lead to the depletion of ozone. The ozone depletion resulted in secondary production of an ozone layer near the ground (terrestrial ozone layer), which is responsible for adverse effects on plants, humans and environment with increased number of bronchial diseases in humans. The mutations caused by UV rays result in variation in morphogenic traits of plants which ultimately decreases crop productivity. However, UV radiation is required in optimum intensity for both plants and animals. This review takes into an account the wide ranging effects of ozone depletion with a majority of them being detrimental to the plant system.
