作者:V. L. Novikov、O. P. Shestak
DOI:10.1007/s11172-013-0316-6
日期:2013.10
A reaction of acetylacetone with equimolar amount of concentrated aqueous H2O2 in both organic solvents (ButOH, AcOH) and water at various temperatures gave the corresponding 3,5-dihydroxy-1,2-dioxolanes with different configuration of stereogenic centers. In the presence of an excess of H2O2, 3,5-dihydroxy-1,2-dioxolanes were converted to a mixture of 5-hydroperoxy-3-hydroxy-1,2-dioxolanes and further to a mixture of dimeric 1,2-dioxolan-3-ylperoxides. All the peroxides formed exist in solutions as equilibrium mixtures with the starting reagents. A prolonged reflux of solutions of 3,5-dihydroxy-1,2-dioxolanes in ButOH in the presence of a large excess of H2O2 led to the skeletal rearrangements of the substrates to a mixture of propionic acid and hydroxyacetone, which underwent further oxidative transformations. Unlike acetylacetone, 2-acetylcyclopentanone reacted with H2O2 in aqueous phase or in solutions in ButOH under thermodynamic or kinetic control with the formation of the corresponding 5-hydroperoxy-3-hydroxy-1,2-dioxolanes, rather than 3,5-dihydroxy-1,2-dioxolanes. Thermodynamically controlled process in solution in AcOH gave a mixture of all four possible hydroperoxyhydroxy-1,2-dioxolanes. These cyclic peroxides in solutions in ButOH or AcOH readily converted to a mixture of AcOH, glutaric, α-methyladipic, and α-hydroxy-α-methyladipic acids. An active α-hydroxylation of the substrate was observed upon reflux of a solution of 2-acetylcyclopentanone and H2O2 in AcOH.
在不同温度下,乙酰丙酮与等摩尔量的浓过氧化氢水溶液在有机溶剂(丁醇、乙酸)和水中的反应,生成了相应的3,5-二羟基-1,2-二氧杂环戊烷,具有不同的立体中心构型。在过氧化氢过量的情况下,3,5-二羟基-1,2-二氧杂环戊烷转化为5-羟过氧基-3-羟基-1,2-二氧杂环戊烷的混合物,进而转化为二聚1,2-二氧杂环戊烷-3-基过氧化物的混合物。所有形成的过氧化物在溶液中以起始试剂的平衡混合物形式存在。在丁醇中3,5-二羟基-1,2-二氧杂环戊烷溶液长时间回流,并在大量过氧化氢存在下,底物发生骨架重排,生成丙酸和羟基丙酮的混合物,进一步经历氧化转化。与乙酰丙酮不同,2-乙酰基环戊酮在水相或丁醇溶液中与过氧化氢反应,在热力学或动力学控制下形成相应的5-羟过氧基-3-羟基-1,2-二氧杂环戊烷,而不是3,5-二羟基-1,2-二氧杂环戊烷。在乙酸溶液中受热力学控制的反应过程生成所有四种可能的羟过氧基羟基-1,2-二氧杂环戊烷的混合物。这些环状过氧化物在丁醇或乙酸溶液中容易转化为乙酸、戊二酸、α-甲基己二酸和α-羟基-α-甲基己二酸的混合物。在乙酸中2-乙酰基环戊酮与过氧化氢溶液回流时,观察到底物的α-羟基化反应活性。