Rotation barriers in aryl- and heteroaryldi(1-adamantyl)methyl systems; the ionic hydrogenation of heteroaryldi(1-adamantyl)methanols
作者:John S. Lomas、Jean-Christophe Lacroix、Jacqueline Vaissermann
DOI:10.1039/a905455c
日期:——
the anti and syn isomers; the latter rotates incompletely to the more stable isomer upon heating, the equilibrium constant ranging from about 5 to 10 at 150 °C, depending on the solvent. Ionic hydrogenation (deoxygenation) of the 2-(3-methylthienyl) alcohols gives a single product, the syn isomer, in which the methyl group is close to the adamantyls; the anti/syn ratio at equilibrium is substantially
[2-(3-甲基噻吩基)]二(1-金刚烷基)甲醇合成为所述的1点01分混合物的抗和顺式异构体; 后者在加热时不完全旋转成更稳定的异构体,根据溶剂的不同,其平衡常数在150°C时约为5至10。2-(3-甲基噻吩基)醇的离子加氢(脱氧)得到单一产物,即顺式异构体,其中的甲基与金刚烷基相近。平衡时的抗/顺式比率显着高于醇的比率。该醇及其脱氧产物中syn →防旋转的活化能(在157°C时)为32.1和34.4 kcal mol –1, 分别。类似的2-(3-甲基呋喃基)衍生物具有低得多的旋转势垒,该醇被分离为稳定的抗旋转异构体。脱氧主要产生相应的甲烷。通过DNMR测定,(2-呋喃基)-,(2-噻吩基)-和(噻唑-2-基)二金刚烷甲醇的抗→顺旋转势垒分别为16.3、20.0和18.2 kcal mol –1。在两种情况下,对2-呋喃醇或其4-甲基衍生物进行脱氧,得到两种异构体,其比例为2∶1,主要是