2－硝基甲基噻唑－4－羧酸乙酯的合成及与丙烯酰胺的缩合

The Synthesis of Ethyl 2 Nitromethyl 4 Carboxylate and Its Condensation Reaction with Acrylamide

２－溴代甲基噻唑－４－羧酸乙酯（Ⅱ）用ＮａＮＯ２或ＡｇＮＯ２硝化，得到２－硝基甲基噻唑－４－羧酸乙酯（Ⅲ）．发现Ⅲ在ＤＭＳＯ中以酸式异构体存在，在ＣＤＣｌ３中以假酸式存在．在Ｍｉｃｈａｅｌ加成条件下，（Ⅲ）与丙烯酰胺缩合，没有得到预期的产物２－〔３′（３′－硝基丙酰胺）〕噻唑－４－羧酸乙酯（Ⅳ）而是得到相当于１，３－偶极加成产物，２－〔３′（５′－酰胺基二氢异口恶唑基）〕噻唑－４－羧酸乙酯（Ⅴ）．

The nitration of ethyl 2 bromomethylthiazole 4 carboxylate (Ⅱ) with NaNO 2 or AgNO 2 gave ethyl 2 nitromethyl 4 carboxylate (Ⅲ). It was found that Ⅲ existed in the aci nitro tautomer in DMSO d 6, and the nitro isomer of Ⅲ was nearly the only form in CDCl 3. Under the Michael reaction condition, Ⅲ condensed with acrylamide to give the 1,3 dipolar addition product, ethyl 2 [3′(5′ amidodihydroisoxazolyl)]thiazole 4 carboxylate (Ⅴ), and not the Michael addition product.