A Mechanistic Study of the Reactions of Geminal Dihalides with LDA. Evidence for a Single Electron Transfer Pathway in the Reaction of Geminal Diiodides
作者:E. C. Ashby、Abhay K. Deshpande、Girish S. Patil
DOI:10.1021/jo00108a032
日期:1995.2
While the reaction of the geminal dichloride, 6,6-dichloro-5,5-dimethyl-1-hexene (8a) with LDA afforded only one product, wh:ich was derived from a chlorocarbene intermediate, the reaction of the corresponding geminal diiodide 8b resulted in the formation of a number of products that were accounted for by a single electron transfer (SET) initiated reaction. This difference in the reactivity patterns of the two substrates shows that the reduction potential of 8b is more favorable than that of 8a and that LDA can function as a one-electron donor. Additionally, 8a was more reactive toward LDA than the already studied monochloro substrate (1a) with the same carbon skeleton. This enhanced reactivity is attributed to the increased acidity of the hydrogen atom attached to the carbon bearing the two chlorine atoms in 8a. The observation that 8b reacted with LDA at a faster rate, not only relative to 8a but also to the corresponding monoiodo compound 1c, indicates that the reduction potential of 8b is more favorable than that of 1c for SET reduction by LDA. Based on the nature of the products formed in the reactions of 8a and 8b with LDA, evidence is presented that supports the notion that, in addition to funtioning as a strong base, LDA can also function as a one-electron donor toward the geminal diiodide 8b.