| Popis: |
Benzophenone-sensitized reactions of 4-diazotetrahydrofuran-3(2H)-ones with H-donors such as tetrahydrofuran, 1,4-dioxane, cyclohexane and diethyl ether, occur without elimination of nitrogen and give rise to the corresponding N-substituted hydrazones or bis-hydrazonoethanes due to a formal insertion of the terminal N atom of diazo group into α-C−H bonds of ethers and aliphatic hydrocarbons, with yields of up to 78 %. Long-wavelength UV irradiation (λ>310 nm) is most suitable for this process, whereas oxygen molecules adequately quench the triplet excited state of the diazoketone and reduce the preparative yields of C−H-insertion products. Hence this photochemical reaction of diazoketones can be used for C−H functionalization of different aliphatic compounds. |
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