芳基硒代酰胺与α-卤代乙酸在醇中的硒转移反应——二烷氧羰基甲基二硒醚的简便合成

Selenium Transfer Reaction of Phenyl or m-Tolyl Selenoamides with α-Haloacetic Acid in Alcohol—the Convenient Synthesis of Bis(alkoxycarbonylmethyl) Diselenides

芳基硒代酰胺与氯乙酸在各种醇中无催化剂下以1∶1和1∶2的比例投入,发生硒转移反应,不同原料投入比下的反应生成了同一种C—Se—Se—C偶联产物——具有多功能团的二烷氧羰基甲基二硒醚,提供了一种新的合成二烷氧羰基甲基二硒醚的简便方法,且反应具有条件温和、产率高、原料易得和选择性好等优点.为了研究该反应机理,选择α-溴代乙酸甲酯或α-溴代乙酸乙酯在无催化剂、中性条件下,乙醇溶液中与苯基硒代酰胺室温下反应,投料比为1∶1和2∶1,结果也都生成了同一类产物二甲氧羰基甲基二硒醚或二乙氧羰基甲基二硒醚,同时还分离得到了相应的副产物苯甲酸乙酯.对该C—Se—Se—C偶联反应发生的可能机理作了推测.

Phenyl or m-tolyl selenoamides reacted with functionalized α-haloacetic acid in 1 ： 1 or 1 ： 2 molar ratio with no catalyst in various alcohols to undergo a selenium transfer reaction. This reaction in different molar ratios furnished the same C-Se-Se-C coupling products with a special structure bis（alkoxycarbonylmethyl） diselenide. A new and facile method for synthesis of such bis（alkoxycarbonylmethyl） diselenides with the advantages of mild reaction conditions, high yields, easy availability of starting materials and good chemical selectivity was provided. In order to investigate the mechanism for this reaction, methyl α-bromoacetate or ethyl α-bromoacetate as starting material was added to the solution of phenyl selenoamide in ethanol in 1 ： 1 or 2 7 1 molar ratio under the neutral condition at room temperature. The resuits indicated that the same product bis（methoxycarbonylmethyl） or bis（ethoxycarbonylmethyl） diselenide was formed. Byproduct ethyl benzoate was also separated. A mechanism for this C-Se-Se-C coupling reaction was proposed.