Development of Novel Synthetic Methods by Utilizing Carbocations and Its Application to Mechanistic Studies

利用碳正离子开发新的合成方法及其在机理研究中的应用

基本信息

批准号：
02453092
负责人：
TAKEUCHI Ken'ichi
金额：
$ 3.58万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

项目摘要

1. Development of New Synthetic Methods for Cage Compounds. 4-Homoadamantanones containing an alkyl or aryl substituent, or deuterium or carbon-13 on the 3-position were synthesized by utilizing our acylative ringexpansion techniqued Meanwhile, a convenient method for the synthesis of 4 (e)-hydroxy- or -methoxy-2-adamantanone was developed by utilizing the solvolysis of easily available 2-oxo-4 (a)-adamantly triflate.2. Development of New System Showing Enhanced Ionization Due to F-Strain. Rigid cage compounds such as (Z)-2-ethylidenebicyclo[2.2.2]oct-l-yl triflate and (Z)-2-ethylidene-l-adamantyl mesylate and halides were found to solvolyze 200-10, 000 times faster than the corresponding E isomers. Molecular mechanics calculations showed that the origin of the enhanced rates is the repulsions between the (Z)-methyl group and the atom in the leaving group that is directly attached to the reaction center.3. Structure of 2-Oxo Cations. The rates of solvolysis of various new 2methylene and 2-oxo bridgehead compounds were determined. The rate data showed that the intermediate carbocation from flexible 2-methylene compounds are stabilized by allylic conjugation, whereas that from the corresponding 2-oxo compounds cannot be stabilized by carbonyl conjugation. The results indicate the unimportance of carbonyl conjugation in carbocations.4. Through-bond Interaction in 3-Oxo Cations. Previously, we proposed that the rates of solvolysis can be enhanced by the stabilization of the intermediate carbocation due to the through-bond interaction of the carbonyl lone-pair with the cationic p orbital. In the present work, 4-oxo-2 (e) adamantly triflate was found to solvolyze assisted by the through-bond interaction. On the other hand, the effect vanished in the solvolysis of 2-aryl-4-oxo-2 (e)-adamantly trifluoroacetate, which gives a highly stable carbocation. The results reinforce the previous. conclusion for the existence of the carbonyl through-bond interaction in carbocations.

1。开发新的笼子化合物合成方法。 4-Homoadamantanones containing an alkyl or aryl substituent, or deuterium or carbon-13 on the 3-position were synthesized by utilizing our acylative ringexpansion techniqued Meanwhile, a convenient method for the synthesis of 4 (e)-hydroxy- or -methoxy-2-adamantanone was developed by utilizing the solvolysis of easily available 2-oxo-4 （a） - 富于三烯酸盐。2。开发新系统显示由于F-strain引起的电离增强。刚性笼子化合物，例如（Z）-2-乙基二烯Bicyclo [2.2.2] OCT-L-基三裂酸盐和（Z）-2-乙基-l-甲基甲基甲酯和卤化物的溶解度为200-10，比相应的E异构体更快。分子力学计算表明，增强速率的起源是（Z） - 甲基基与直接连接到反应中心的离开组中的原子之间的排斥。3。 2氧阳离子的结构。确定了各种新2m甲基和2-氧化桥头化合物的溶解度速率。速率数据表明，来自柔性2-甲基化合物的中间型碳酸盐通过烯丙基共轭稳定，而从相应的2-氧化物化合物中不能通过羰基结合稳定。结果表明羰基共轭不重要。4。 3氧化阳离子中的贯用相互作用。以前，我们提出，由于羰基单对与阳离子p轨道的循环相互作用，可以通过稳定中间碳分配来提高溶解度的速率。在目前的工作中，发现4-氧基-2（E）被认为是通过汇聚相互作用辅助溶解的。另一方面，在2- Aryl-4-oxo-2（e）的溶解度中消失的效果消失了，这给了高度稳定的碳酸盐。结果加强了上一个。结论羰基在碳中存在键合的相互作用。