Comparison of the electronic effect and the steric influence between the 1,1,2,2,2-pentamethyldisilanyl and the trimethylsilyl groups
作者:Jih Ru Hwu、John M. Wetzel、John S. Lee、Raymond J. Butcher
DOI:10.1016/0022-328x(93)80322-3
日期:1993.6
A comparison of the electronic effects expressed by the Me3SiMe2Si-; and Me3Si- groups towards carbocationic intermediates was made by study of acid-catalyzed rearrangements of decalin epoxides 3 and 4. Reaction of the Me3SiMe2Si-epoxide 3 with BF3 · Et2O in CH2Cl2 at -50°C gave four products: B-ring contracted spirocyclic alcohol 9 (21%), methyl-migrated decanol 12 (23%), A-ring contracted aldehyde
Me 3 SiMe 2 Si-;表示的电子效应的比较;通过研究十氢化萘环氧化物3和4的酸催化重排,制得了朝向碳阳离子中间体的Me和Si 3和Si 3-。Me 3 SiMe 2 Si-环氧化合物3与BF 3 ·Et 2 O在CH 2 Cl 2中在-50°C下反应,得到四种产物:B环缩合的螺环醇9(21%),甲基迁移的癸醇12( 23%),A环缩醛15(21%)和氟代醇17(14%)。在相同条件下中,Me 3 Si的环氧化物4,得到醇9(24%),癸醇12(18%),醛16(23%; CF。15),和fluorohydrin 18(13%; CF。17)。这些结果表明,Me 3 SiMe 2 Si-和Me 3 Si-基团对碳正离子具有相同程度的电子影响。