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Mechanisms of the Au- and Pt-Catalyzed Intramolecular Acetylenic SchmidtReactions: A DFT Study
Xia, Yuanzhi; Huang, Genping
2010
Source PublicationJOURNAL OF ORGANIC CHEMISTRY
ISSN0022-3263
Volume75Issue:22Pages:7842-7854
AbstractThe reaction mechanisms of the PtCl(4)- and Au(I)-catalyzed intramolecular acetylenic Schmidt reactions were analyzed by means of hybrid density functional calculations at the B3LYP/6-31G*(LANL2DZ) level of theory for better understanding of the acceleration effect of ethanol solvent in PtC(4)-catalyzed reaction and the different catalytic activities of Au and Pt catalysts Calculations indicate the rate of the PtCl(4)-catalyzed reaction in noncoordinative solvent of 1,2-dichloroethane is limited by isomerization of the relatively stable chelate complex to the reactive pi-complex of PtCl(4) with the acetylenic moiety of homopropargyl azide substrate, which requires an activation energy of 29 6 kcal/mol All nudeophilic cyclization, dinitrogen elimination, and 1,2-H shift of metal-carbene steps are quite facile The generation of 2H-pyrrole intermediate in PtCl(4)-catalyzed reaction is completed by a ligand substitution reaction, and the final 2H-pyrrole to 1H-pyrrole isomerization is an intermolecular process with another 2H-pyrrole as a proton shuttle When in ethanol solution, the favorable coordination of solvent molecules with PtCl(4) could inhibit the chelation of PtCl(4) with the homopropargyl azide Besides, the alcohol coordination also facilitates the generation of 2H-pyrrole intermediate and the intermolecular isomerization of 2H-pyrrole to 1H-pyrrole Consequently, the overall activation barrier of PtCl(4)-catalyzed reaction in ethanol solution is lowered to 215 kcal/mol, determined by the H-abstraction step of the intermolecular 2H-pyrrole to 1H-pyrrole isomerization The basic steps in the Au(I)-catalyzed reaction are similar to those in the PtCl(4)-catalyzed one However, no chelate complex could be formed from PR(3)AuSbF(6) and homopropargyl azide, and the 2H-pyrrole generation step is much more favorable, indicating weaker interactions of Au(I) catalyst with the homopropargyl azide and the C C double bond of 2H-pyrrole The reaction mechanisms of the PtCl(4)- and Au(I)-catalyzed intramolecular acetylenic Schmidt reactions were analyzed by means of hybrid density functional calculations at the B3LYP/6-31G*(LANL2DZ) level of theory for better understanding of the acceleration effect of ethanol solvent in PtC(4)-catalyzed reaction and the different catalytic activities of Au and Pt catalysts Calculations indicate the rate of the PtCl(4)-catalyzed reaction in noncoordinative solvent of 1,2-dichloroethane is limited by isomerization of the relatively stable chelate complex to the reactive pi-complex of PtCl(4) with the acetylenic moiety of homopropargyl azide substrate, which requires an activation energy of 29 6 kcal/mol All nudeophilic cyclization, dinitrogen elimination, and 1,2-H shift of metal-carbene steps are quite facile The generation of 2H-pyrrole intermediate in PtCl(4)-catalyzed reaction is completed by a ligand substitution reaction, and the final 2H-pyrrole to 1H-pyrrole isomerization is an intermolecular process with another 2H-pyrrole as a proton shuttle When in ethanol solution, the favorable coordination of solvent molecules with PtCl(4) could inhibit the chelation of PtCl(4) with the homopropargyl azide Besides, the alcohol coordination also facilitates the generation of 2H-pyrrole intermediate and the intermolecular isomerization of 2H-pyrrole to 1H-pyrrole Consequently, the overall activation barrier of PtCl(4)-catalyzed reaction in ethanol solution is lowered to 215 kcal/mol, determined by the H-abstraction step of the intermolecular 2H-pyrrole to 1H-pyrrole isomerization The basic steps in the Au(I)-catalyzed reaction are similar to those in the PtCl(4)-catalyzed one However, no chelate complex could be formed from PR(3)AuSbF(6) and homopropargyl azide, and the 2H-pyrrole generation step is much more favorable, indicating weaker interactions of Au(I) catalyst with the homopropargyl azide and the C C double bond of 2H-pyrrole
Indexed BySCI
Document Type期刊论文
Identifierhttp://ir.isl.ac.cn/handle/363002/1896
Collection青海盐湖研究所知识仓储
Recommended Citation
GB/T 7714
Xia, Yuanzhi,Huang, Genping. Mechanisms of the Au- and Pt-Catalyzed Intramolecular Acetylenic SchmidtReactions: A DFT Study[J]. JOURNAL OF ORGANIC CHEMISTRY,2010,75(22):7842-7854.
APA Xia, Yuanzhi,&Huang, Genping.(2010).Mechanisms of the Au- and Pt-Catalyzed Intramolecular Acetylenic SchmidtReactions: A DFT Study.JOURNAL OF ORGANIC CHEMISTRY,75(22),7842-7854.
MLA Xia, Yuanzhi,et al."Mechanisms of the Au- and Pt-Catalyzed Intramolecular Acetylenic SchmidtReactions: A DFT Study".JOURNAL OF ORGANIC CHEMISTRY 75.22(2010):7842-7854.
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