已经制备了2-烯丙氧基链烷酸(1)和丙-2-炔氧基乙酸的酰肼(3)和(4)。然后,通过与苯甲酰氯反应,将这些酰肼分别转化为the(6)和(7)。通过与碳酸钠反应,由生成了偶氮烯烃。分离的产物是由偶氮烯烃的自发分子内环加成反应形成的哒嗪-恶嗪酮(8)[来自(6)]和(9)[来自(7)]。(6b)和(6c)具有不相邻于羰基的不对称碳中心的化合物各自产生非对映异构的恶嗪的混合物,但是在每种情况下具有相当大的选择性(6:1)。这归因于过渡态中的空间效应。用衍生自酰肼(3)和(4)的和溴代丙酮酸乙酯进行了一系列类似的转化。还已经制备了N-乙酰基-N-烯丙基甘氨酸酰肼(11)。通过与碳酸钠反应,将由该酰肼和苯甲酰氯形成的hydr (13)转化为偶氮烯,将其环化,得到吡嗪并[1,2 - b ]哒嗪-8-一(14a)。)。
Silica-supported HClO<sub>4</sub> promotes catalytic solvent- and metal-free O–H insertion reactions with diazo compounds
作者:Rafael Douglas C. Gallo、Antonio C. B. Burtoloso
DOI:10.1039/c8gc02574f
日期:——
employing rhodium acetate dimer, this method uses eco-friendly silica-supported HClO4 as the catalyst. Only 0.3 mol% of this Brønsted acid catalyst, that can also be recycled several times, is necessary to guarantee very good yields (up to 97%) in the O–H insertion reactions. Reaction set-up is simple and permitted the preparation of forty-three α-hydroxy and α-alkoxy esters/ketones in just 1 h and at room