A novel reactivity of α-nitro ketone tosylhydrazones with DBU. Synthesis of α,β-unsaturated enone tosylhydrazones
作者:Roberto Ballini、Gianni Giantomassi
DOI:10.1016/0040-4020(95)00133-s
日期:1995.4
Treatment of α-nitro ketone tosylhydrazones with DBU gives 1,4-elimination of nitrous acid affording 1-tosylazoalkenes which, under basic conditions (DBU), tautomerize to the more stable enone tosylhydrazones. The obtained tosylhydrazones may be used as starting material for a wide range of other functionalities. Removal of the hydrazone affords conjugated enones in good yields. Due to the possibility
(Z)-Jasmone ,dihydrojasmone and other 3-methylcyclo=pent-2-en-1-ones are easily synthesized starting from aldehydes and 1-(2-methyl-1,3-dioxolane-2-yl)-2-nitroethane as reagent for 3-ketobutyl anion synthon. Nitro-aldol condensation is the chainlegthening reaction followed by oxidation and denitration via p-toluenesulfonylhydrazones of the corresponding α-nitroke=tones. Removal of protecting groups