Design of metal-catalyzed synthetic reactions based on theoretical calculations

1) Friedel-Crafts反应是典型的亲电芳取代反应，由Lewis酸催化。确切的反应机理尚未阐明。需要了解典型Lewis酸Al_2Cl_6桥接形式的催化能力、惠兰中间体质子消去的驱动力和速率决定步骤。用6-31G^*基集对氯化铝催化苯与乙酰氯的Friedel-Crafts酰化反应进行了B3LYP密度泛函理论计算。首先羰基氧配位到Al，得到的配合物异构化为酰基离子中间体（π-配合物）。亲电加成后形成惠兰中间体（σ-络合物）。从而阐明了基本过程。目前，对Friedel-Crafts烷基化反应的研究正在进行中。2)对四甲基和四甲基二苯二烯的醇和酚添加量进行了密度泛函和ononom计算。MeOH的二聚体比单体更容易加入Me_2Si = SiMe_2。三聚体产生的不是加合物，而是两性离子中间体。（CF_3OH）_2加入到Me_2Si = SiMe_2中，H......Si键的形成比O键更早....过渡态（TS）的Si键形成。研究了7种苯酚衍生物在Me_2Si = SiMe_2上的加成反应，发现无论苯环上是否有取代基，二聚体反应都优于单体反应。（MeOH）_2与Mes_2Si = SiMes_2反应良好，类反应物配合物（前驱体）的异构体可通过内旋形成不同立体化学性质的加合物。通常，醇或酚的二聚体是二烯的反应物。特殊的是，对（二甲氨基）苯酚单体与Mes_2Si = SiMes_2发生反应是由于四个甲酰基的空间阻塞。

1) The Friedel-Crafts reaction is a representative electrophilic aromatic substitution reaction, catalyzed by Lewis acids. The precise reaction mechanism has not been elucidated yet. Understanding of catalytic ability of the bridged form of a typical Lewis acid Al_2Cl_6, the driving force for proton elimination of Wheland intermediate, and rate-determining step is required. B3LYP density functional theory calculations with 6-31G^* basis set of Friedel-Crafts aclylation reaction of benzene with acetyl chloride catalyzed by aluminum chloride were carried out. At first, carbonyl oxygen coordinates to Al and the resulting complex isomerizes to acylium ion intermediate (π-complex). After the electrophilic addition, Wheland intermediate (σ-complex) forms. Thus, the elementary process was elucidated. The study on Friedel-Crafts alkylation is currently under investigation.2) Density functional and ONIOM calculations of alcohol and phenol additions to two (tetramethyl and tetramesityl) dislenes were carried out. The dimer of MeOH adds to Me_2Si = SiMe_2 more readily than the monomer. The trimer gives not the adduct but a zwitter-ionic intermediate. In the (CF_3OH)_2 addition to Me_2Si = SiMe_2, the H......Si bond formation is more advanced than the O....Si bond formation at the transition state (TS). Additions of seven phenol derivatives to Me_2Si = SiMe_2 were examined, and the dimer reactions were found to be better than the monomer reaction regardless of the substituents on benzene rings. (MeOH)_2 reacts also with Mes_2Si = SiMes_2 favorably, and an isomer of the reactant like complex (precursor) may afford an adduct of the different stereochemistry via internal rotations. Generally, the dimer of the alcohol or phenol is the reactant toward the disilenes. Exceptionally, a monomer of p-(dimethylamino)phenol reacts with Mes_2Si = SiMes_2 owing to the steric congestion by four mesityl groups.