DFT Investigation on Mechanisms and Stereoselectivities of [2 + 2 + 2] Multimolecular Cycloaddition of Ketenes and Carbon Disulfide Catalyzed by N-Heterocyclic Carbenes

• DOI: 10.1021/jo4018809
• Publication Date: 2013-11-04T14:49:17Z
• Authors: Wen-Jing Zhang; Dong-Hui Wei; Ming-Sheng Tang
• Keywords: 01 natural sciences; 0104 chemical sciences; 3. Good health

The first theoretical investigation using density functional theory (DFT) methods to study the detailed reaction mechanisms of stereoselective [2 + 2 2] multimolecular cycloaddition ketene (two molecules) and carbon disulfide (CS2, one molecule) which is catalyzed by N-heterocyclic carbene (NHC) presented in this paper. calculated results indicate that occurs through four steps: complexation NHC with (channel 1a) rather than CS2 1b), addition 2b) but not dimerization 2a), formal [4 a second molecule 3a) intramolecular 3b), finally regeneration NHC. step revealed be rate-determining step. Moreover, stereoselectivities associated chiral center double bond are predicted respectively determined third steps R E configurations dominated, good agreement experimental results. Furthermore, possible identical N,N-dimethylpyridin-4-amine (DMAP) have also been investigated help understand ring closure mechanism proceeding