CAJ | 학술논문

采用密度泛函理论(DFT)方法研究了在还原剂(EtO)3SiH存在下,铜(I)(Cl2IPrCuF)催化CO2插入1-苯基丙炔生成α,β不饱和羧酸的反应机理.计算结果表明, Cl2IPrCuF首先与(EtO)3SiH生成活性催化剂Cl2IPrCuH,然后经历三个步骤完成催化反应：(1) Cl2IPrCuH与1-苯基丙炔加成生成烯基铜中间体.由于炔烃的不对称性,烯基铜中间体有两种同分异构体,最后可导致生成两种对应的α,β不饱和羧酸衍生物；(2) CO2插入烯基铜中间体得到羧基铜中间体；(3)(EtO)3SiH与羧基铜中间体发生σ转位反应形成最终产物,同时重新生成催化剂Cl2IPrCuH.理论研究还表明,生成两种α,β不饱和羧酸衍生物的反应路径所对应的决速步骤不同,在Path a中炔烃插入反应和CO2插入反应都可能是整个催化反应的决速步骤,自由能垒分别为68.6和67.8 kJ?mol-1,而在Path b中,仅炔烃插入反应是整个催化反应的决速步骤,自由能垒为78.7 kJ?mol-1.此结果很好地给出了实验上两种α,β不饱和羧酸衍生物收率不同的原因.炔烃与Cl2IPrCuH的加成决定了反应的区域选择性,其中电子效应是影响反应区域选择性的主要原因.
채용밀도범함이론(DFT)방법연구료재환원제(EtO)3SiH존재하,동(I)(Cl2IPrCuF)최화CO2삽입1-분기병결생성α,β불포화최산적반응궤리.계산결과표명, Cl2IPrCuF수선여(EtO)3SiH생성활성최화제Cl2IPrCuH,연후경력삼개보취완성최화반응：(1) Cl2IPrCuH여1-분기병결가성생성희기동중간체.유우결경적불대칭성,희기동중간체유량충동분이구체,최후가도치생성량충대응적α,β불포화최산연생물；(2) CO2삽입희기동중간체득도최기동중간체；(3)(EtO)3SiH여최기동중간체발생σ전위반응형성최종산물,동시중신생성최화제Cl2IPrCuH.이론연구환표명,생성량충α,β불포화최산연생물적반응로경소대응적결속보취불동,재Path a중결경삽입반응화CO2삽입반응도가능시정개최화반응적결속보취,자유능루분별위68.6화67.8 kJ?mol-1,이재Path b중,부결경삽입반응시정개최화반응적결속보취,자유능루위78.7 kJ?mol-1.차결과흔호지급출료실험상량충α,β불포화최산연생물수솔불동적원인.결경여Cl2IPrCuH적가성결정료반응적구역선택성,기중전자효응시영향반응구역선택성적주요원인.
Density functional theory (DFT) calculations have been used to conduct a detailed study of the mechanism involved the copper(I)-catalyzed hydrocarboxylation of 1-phenyl-propyne using CO2 and hydrosilane. Theoretical calculations suggested that the activated catalyst Cl2IPrCuH is initial y generated in situ by the reaction of Cl2IPrCuF with (EtO)3SiH, and that the entire catalytic reaction involves three steps, including (1) the addition of Cl2IPrCuH to 1-phenyl-propyne to afford two isomeric copper alkenyl intermediates, which lead to the formation of the corresponding finalα,β-unsaturated carboxylic acid derivatives;(2) CO2 insertion to give the corresponding copper carboxylate intermediate; and (3) σ-bond metathesis of the copper carboxylate intermediate with a hydrosilane to provide the corresponding silyl ester with the regeneration of the active catalyst. The results of our calculations show that the rate-limiting steps for the two paths leading to the twoα,β-unsaturated carboxylic acid derivatives are different. In Path a, the alkyne and CO2 insertion steps were both identified as possible rate-limiting steps, with free energy barriers of 68.6 and 67.8 kJ?mol-1, respectively. However, in Path b, the alkyne insertion step was identified as the only possible rate-limiting step with an energy barrier of 78.7 kJ?mol-1. These results were in agreement with the experimental observations. It was also found that the alkyne insertion step control ed the regioselectivity of the products, and that electronic effects were responsible for the experimentally observed regioselectivity.