作者:Sergeja Bombek、Franc Požgan、Marijan Kočevar、Slovenko Polanc
DOI:10.1039/b502719e
日期:——
We report on the reactions of diazenes 1 and 2 with 1,3-dicarbonyl compounds. The first step involves a regioselective attack of the diazene on the active methylene group, giving the Michael adducts 3 or 4, and can be performed either in the presence of sodium acetate or DBN (1,5-diazabicyclo[4.3.0]non-5-ene). The Michael adducts underwent ring-closure leading to 2-imidazolidinones 5 or 6 which were isolated in some cases. We found that 5 or 6 easily eliminated water in the presence of an acid to give imidazolin-2-ones 7 or 8 as the final products. The rate-determining step of this last mentioned process depends on the stereochemistry at C4 and C5 of the initial 2-imidazolidinone. A one-pot procedure to produce 7 or 8 directly from the diazene and the appropriate dicarbonyl partner is also described.
我们报道了重氮化合物1和2与1,3-二羰基化合物的反应。第一步涉及重氮化合物选择性地攻击活性亚甲基,形成迈克尔加合物3或4,可以在醋酸钠或DBN(1,5-二氮双环[4.3.0]壬-5-烯)的存在下进行。迈克尔加合物经过环闭合反应,生成了2-咪唑啉酮5或6,某些情况下可以分离得到。我们发现5或6在酸性条件下容易脱水,生成最终产物咪唑啉-2-酮7或8。刚才提到的这一最后步骤的速率决定步骤取决于初始2-咪唑啉酮在C4和C5的立体化学。我们还描述了一个一步法程序,直接从重氮化合物与适当的二羰基化合物生成7或8。