Towards Configurationally Stable [4]Helicenes: Enantioselective Synthesis of 12-Substituted 7,8-Dihydro[4]helicene Quinones
作者:M. Carmen Carreño、Álvaro Enríquez、Susana García-Cerrada、M. Jesús Sanz-Cuesta、Antonio Urbano、Feliu Maseras、Alfons Nonell-Canals
DOI:10.1002/chem.200700762
日期:2008.1.7
The size of this group was also defining the configurational stability of the final (P)-7,8-dihydro[4]helicene quinones 4 and 5. The interconversion barriers between the P and M helimers in the latter, computed with a DFT B3LYP method, matched well with the experimentally observed stability. Our study provided evidence that, in addition to steric effects, a small but significant role of electronic effects
对映体纯的C-12甲氧基或烷基取代的5,7,8,12b-四氢[4] hel烯醌16和17以及7,8-二氢芳族类似物4和5的合成已从(SS)-2 -(对甲苯基亚磺酰基)-1,4-苯醌。在第一个系列中,具有既包含中心手性又包含螺旋手性的结构,立体碳原子的R绝对构型是在不对称环加成步骤后定义的,而P或M的螺旋性则取决于C-的性质。 12个取代基。该组的大小还定义了最终的(P)-7,8-二氢[4] ic烯醌4和5的构型稳定性。使用DFT B3LYP计算的后者中P和M直升机之间的相互转换势垒方法,与实验观察到的稳定性非常匹配。我们的研究提供了证据,