Mechanism of Reaction of Geminal Dihalides with Lithium Naphthalenide (LiNp(.-)): Evidence for an Electron Transfer Mechanism. Similarities to the Mechanism of Reaction of Geminal Dihalides with Certain Nucleophiles and Other One-Electron Donors

Article abstract of DOI:10.1021/jo00119a034

The reactions of the sterically hindered geminal dihalides 6,6-dichloro-5,5-dimethyl-1-hexene (1a) and 6,6-diiodo-5,5-dimethyl-1-hexene (1b) with lithium naphthalenide (LiNp(.-)) in THF were investigated in an attempt to compare the results of reactions involving a known one-electron donor (LiNp(.-)) with those involving nucleophiles believed to be one-electron donors.On the basis of radical-trapping studies, deuterium tracer studies, and product studies using cyclizable radical probes, it can be concluded that the reactions studied are very similar to those reported by us earlier involving magnesium metal, LiAlH4, and other nucleophiles.In addition to radical-derived products, the reaction of 1a with LiNp(.-) afforded hydrocarbons, in high yields, that were derived from a carbene intermediate.On the other hand, 1b, on reaction with LiNp(.-), did not yield any carbene-derived hydrocarbons.These results show that the formation of a carbene intermediate, derived from a radical, depends on the nature of the halogen present.It was also found that naphthalene can behave as a hydrogen atom donor toward a radical in the presence of known hydrogen atom donors, such as THF.