威尔金森催化剂快速合成咖啡呋喃及其反应机理

Rapid synthesis of coffee furan by Wilkinson catalyst andits reaction mechanism

咖啡呋喃的人工合成路线复杂、收率低。以3-噻吩甲醇为原料,得到关键中间体2-乙酰基-3-噻吩甲醇,并以此为底物,可快速合成咖啡呋喃。考察合成关键底物的原料与醋酸酐物质的量比对收率的影响,并推导验证反应机理。结果表明,关键步骤噻吩环的2位乙酰化反应中,最佳原料比为n(原料)∶n(醋酸酐)=1.2;威尔金森催化剂在加氢条件下能催化2-乙酰基-3-噻吩甲醇分子内环合反应,简便快速地合成咖啡呋喃;威尔金森催化剂催化邻羟甲基羰基化合物分子内环合反应可能经历分子内半缩酮脱水和催化加氢还原。

The synthetic route of coffee furan is complex and the yield is low.Using 3-thiophenyl alcohol as raw material,the key intermediate 2-acetyl-3-thiophenyl alcohol was obtained,and the coffee furan could be quickly synthesized from this substrate.The effect of the ratio of raw material to acetic anhydride on the yield of the key substrate was investigated,and the reaction mechanism was deduced and verified.The results showed that in the 2-site acetylation reaction of thiophene ring,the optimal ratio of raw material to acetic anhydride was 1.2.Wilkinson catalyst can catalyze the intramolecular cyclation of 2-acetyl-3-thiophenyl carbinol under hydrogenation conditions,and can easily and quickly synthesize cafefuran.The intramolecular cyclization reaction of o-hydroxymethylcarbonyl compounds catalyzed by Wilkinson catalyst may undergo intramolecular half-acetone dehydration and catalytic hydrogenation reduction.