4516-69-2Relevant articles and documents
A Photochemical Probe for Single Electron Transfer in Nucleophilic Aliphatic Substitution: Evidence for Geminate Radical Coupling in the Solvent Cage
Tolbert, Laren M.,Sun, Xiao-Jing,Ashby, E.C.
, p. 2681 - 2685 (1995)
A major effort to establish single electron transfer (SET) as an important pathway in nucleophilic aliphatic substitution reactions has involved the use of cyclizable probes, e.g., 6-iodo-5,5-dimethyl-1-hexene.In order to examine the partition between cyclization and direct radical-radical recombination, we have investigated the ground-state and excited-state chemistry of the 9-phenylfluorenyl anion (9PF-) with neopentyl-type iodides.It has been shown that 9PF- does not react with Me3CCH2I, but it does undergo efficient reaction upon irradiation (Φ=1.0) to yield nucleophilic aliphatic substitution products.With the sterically analogous cyclizable probe 6-iodo-5,5-dimethyl-1-hexene, no ground-state reaction is observed.However, both cyclized and uncyclized products of substitution, 9PFRc and 9PFRu, are produced upon irradiation.Thus photoproducts clearly involving electron-transfer-induced radical intermediates can result without acommpanying free-radical cyclization.These results suggest that, although the observation of cyclized products in the reaction of a cyclizable radical probe with a nucleophile is evidence of a radical intermediate, the absence of such cyclized products does not require the absence of radical intermediates.
Electron Transfer in the Reactions of Geminal Dihalides with Ph2P(-). Evidence for the Formation of a Carbene Intermediate from a Radical Precursor
Ashby, E. C.,Deshpande, Abhay K.
, p. 7117 - 7124 (2007/10/03)
The reactions of two sterically hindered geminal dihalides, 6,6-dichloro-5,5-dimethyl-1-hexene (5a) and 6,6-diiodo-5,5-dimethyl-1-hexene (5b), with Ph2P(-) have been found to involve a single electron transfer (SET) pathway.Since the corresponding monochl
Mechanism of Reaction of Geminal Dihalides with Magnesium. Evidence for the Formation of Carbenes from Radical Precursors. The Similarity in Reactions of Geminal Dihalides with Magnesium and LiAlH4
Ashby, E. C.,Deshpande, Abhay K.,Doctorovich, Fabio
, p. 6223 - 6232 (2007/10/02)
The geminal dihalides, 6,6-dichloro-5,5-dimethyl-1-hexene (2a) and 6,6-diiodo-5,5-dimethyl-1-hexene (2b) were allowed to react with Rieke activated magnesium (Mg*) in THF at 25 deg C.Both radical and carbene intermediates were identified by product analyses, by radical trapping experiments using DCPH and THF-d8, and by selective experiments in which isolated intermediates were shown to form the predicted products.Although carbene products predominated over radical products when the dichloride was allowed to react with Mg*, radical products predominated when the diiodide was allowed to react with Mg*.Evidence is presented that indicates that the carbene intermediate arises from a radical precursor.A mechanistic scheme (Scheme 5) is presented that is consistent with all of the observed data.A comparison of the reactions of 2b with Mg* and 2b with LiAlH4 shows that most of the products are common in both reactions thereby providing further evidence for LiAlH4 as a one-electron donor, as is known behavior of Mg*.
