• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Tetrahedron >ORIGIN OF PI-FACIAL STEREOSELECTIVITY OF HYDRIDE REDUCTION OF CYCLOHEXANONES - A NEW INTERPRETATION BASED ON QUANTITATIVE ANALYSIS OF EXTERIOR FRONTIER ORBITAL EXTENSION
【24h】

ORIGIN OF PI-FACIAL STEREOSELECTIVITY OF HYDRIDE REDUCTION OF CYCLOHEXANONES - A NEW INTERPRETATION BASED ON QUANTITATIVE ANALYSIS OF EXTERIOR FRONTIER ORBITAL EXTENSION

机译：环己酮氢化物还原的PI面立体选择性的起源-基于外部前沿轨道扩展定量分析的新解释

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

A new theoretical interpretation for pi-facial stereoselectivity of hydride reduction of cyclohexanones has been proposed based on the simple assumption that the lowest unoccupied molecular orbital (LUMO) of the substrates should play an essential role in the reaction: pi-Facial stereoselectivity is described by relative magnitude of exterior frontier orbital extension (EFOE) of the LUMO above or below the carbonyl plane, which is defined by integrated ''hole density'' of the LUMO at the carbonyl carbon over three-dimensional spatial points outside repulsive molecular surface, where the absolute total value of the gaussian functions belonging to the carbonyl carbon makes the maximum contribution to the total value of the LUMO wave function so that the driving force vector on hydride is maximally directed toward the carbonyl carbon. A good linear correlation is observed for ten alkyl-substituted cyclohexanones (NaBH4 in 2-propanol) between the difference in the square of EFOE densities for the axial (EFOE(ax)) and equatorial (EFOE(eq)) areas (lambda = EFOE(ax)(2) - EFOE(eq)(2)) and the difference in activation enthalpy for equatorial (Delta H-eq(double dagger)) and axial (Delta H-ax(double dagger)) attack (Delta Delta H double dagger = Delta H double dagger(eq) - Delta H-ax(double dagger)). (C) 1997 Elsevier Science Ltd. [References: 42]
机译：基于简单的假设，即底物的最低未占据分子轨道（LUMO）应在反应中起重要作用，提出了一种对环己酮的氢化物还原的π面立体选择性的新理论解释：羰基平面以上或以下的LUMO的外部前沿轨道延伸（EFOE）的相对大小，其由排斥分子表面外部三维空间点上羰基碳上LUMO的积分``空穴密度''定义，其中属于羰基碳的高斯函数的绝对总和对LUMO波函数的总值有最大的贡献，因此氢化物上的驱动力矢量最大程度地指向羰基碳。对于轴向（EFOE（ax））和赤道（EFOE（eq））区域的EFOE密度平方差（λ= EFOE），观察到十个烷基取代的环己酮（2-丙醇中的NaBH4）有良好的线性相关性（ax）（2）-EFOE（eq）（2））以及赤道（Delta H-eq（双匕首））和轴向（Delta H-ax（double dagger））攻击（Delta Delta H double dagger = Delta H double dagger（eq）-Delta H-ax（double dagger））。 （C）1997 Elsevier Science Ltd. [参考：42]

著录项

相似文献

  • 外文文献
  • 中文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号