Ab initio molecular orbital study on three feasible mechanisms for substitution of the vinylic carbon in F2C=C(OMs)BMe3−

✍ Scribed by Kenzi Hori; Shohei Fukuda; Junji Ichikawa

• Book ID: 104209777
• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 703 KB
• Volume: 55
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(99)00976-x

✦ Synopsis

A substitution on 2,2-difluorovinyhc carbon was investigated by using a6 initio molecular orbital calculations. Three feasible mechanisms, which are the S,l-like, the S,2-type and the addition-elimination mechanisms, were examined for a model borate, 2,2-difluoro-l-mesyloxyvinyl(trimethyl)borate. Four TSs were obtained depending on the position of Li' around the vinylborate although activation energies in the gas phase are rather high (ca. 30-40 kcal mol') in comparison with that expected from the experimental conditions. It was confnmed at the SCRF-IPCM calculations that the solvent effect reduces the activation energy of one S,2-type mechanism very much (4.1 kcal mol-' at the B3LYP/6-31+G*//RHF/6_31+G* leve1 of theorv) while those for tbe other mechanisms do not change very much. Therefore: the S,2-type mechanism is applicable to tbe substitution reaction observed for tbe vinylborate.