Epimerization of Tertiary Carbon Centers via Reversible Radical Cleavage of Unactivated C(sp<sup>3</sup>)–H Bonds
作者:Yaxin Wang、Xiafei Hu、Cristian A. Morales-Rivera、Guo-Xing Li、Xin Huang、Gang He、Peng Liu、Gong Chen
DOI:10.1021/jacs.8b05753
日期:2018.8.1
cleavage of C(sp3)-H bonds can enable racemization or epimerization, offering a valuable tool to edit the stereochemistry of organic compounds. While epimerization reactions operating via cleavage of acidic C(sp3)-H bonds, such as the Cα-H of carbonyl compounds, have been widely used in organic synthesis and enzyme-catalyzed biosynthesis, epimerization of tertiary carbons bearing a nonacidic C(sp3)-H bond
perhydroindane product by means of mass spectrometry and 13C NMR spectroscopy. The results prove that C-O bond scission takes place primarily through the direct hydrogenolysis pathway on the carbon-supported catalysts. Direct hydrogenolysis occurs on the carbon support because of the formation of a better leaving group (OH2+) from the benzylic hydroxy group and its subsequent substitution by spillover
来自各种来源且具有不同铑分散体的氧化铝负载催化剂在1-茚醇的液相加氢中主要产生氢化产物perhydro-1-indanol,而碳负载催化剂主要产生CO键断裂-氢化产物过氢茚满。向反应混合物中加入有机或无机碱抑制了CO键的断裂。为了区分直接氢解或脱水然后氢化的CO键断裂的两种可能途径,已经用碳载催化剂进行了氘代研究。不仅使1-茚满醇而且使茚满和茚(CO键断裂路径中的两种可能的机理中间体)氘化。已通过质谱和13 C NMR光谱测定氘化程度和氘在所得过氢茚满产物中的掺入位置,从而获得了有关实际途径的信息。结果证明,CO键的断裂主要通过碳载催化剂上的直接氢解途径发生。由于在苄基羟基上形成了更好的离去基团(OH2 +),随后碳氢载体上发生了直接氢解,随后氢被溢出氢取代。
Djakowa; Losowoi, Zhurnal Obshchei Khimii, 1939, vol. 9, p. 26,31
作者:Djakowa、Losowoi
DOI:——
日期:——
Selective functionalization of hydrocarbons. 6. Mechanistic and preparative studies on the regio- and stereoselective paraffin hydroxylation with peracids
作者:Hans Joerg Schneider、Walter Mueller
DOI:10.1021/jo00223a036
日期:1985.11
Regioselective cyclopentane ring formation mediated by titanocene chloride
作者:Pascal Rigollier、Jonathan R. Young、Lissa A. Fowley、John R. Stille