ヘテロ芳香族性の研究(第6報)

アセチレン基を含むフラン誘導体の合成

抄録

Furfural, 5-bromo-2-furfural, and 5-nitro-2-furfural were treated in tetrahydrofuran with ethynylmagnesium bromide to give the corresponding furylethynylcarbinols in yields of 35, 22, and 6%, respectively. Furfural afforded furylpropargylcarbinol in only 2% yield, when treated with propargyl magnesium bromide in ether . Oxidative coupling reaction and the Mannich reaction were carried out using furylethynylcarbinol. Mercury derivatives of furyl- and 5-bromo-2-furyl ethynylcarbinols were prepared by the McEwen's method. The sodium acetylide of furylethynylcarbinol was condensed with ethyl chlorocarbonate . The preparative method of 5-nitro-2-furylpropiolic acid was reinvestigated and the yield was improved up to 60%. 5-Nitro-2-furylacetylene was synthesized by the following three methods: 1) decarboxylation of 5-nitro-2-furylpropiolic acid, 2) dehydrobromination of 5-nitro-2-furylbrornoethylene, and 3) dehydrobromination of β-(5-nitro-2-furyl)-α-bromopropenal. Though the oxidative coupling reaction and mercuration of 5-nitro-2-furylacetylene proceeded smoothly, the Mannich reaction did not take place.