77400-57-8Relevant academic research and scientific papers
Mechanism of Reaction of Geminal Dihalides with Lithium Aluminum Hydride. Evidence for Single Electron Transfer as the Major Reaction Pathway
Ashby, E. C.,Deshpande, Abhay K.
, p. 3798 - 3805 (2007/10/02)
The reactions of a sterically hindered geminal dichloride 4a and the corresponding diiodide 4b with LiAlH4 (LAH) were found to involve an electron-transfer mechanism.Whereas the monochloro analog of 4a (8) is inert toward LAH, 4a was more reactive.Observation of radical-derived products in the reaction of 4a with LAH indicates that the presence of two chlorine atoms on the same carbon atom results in a favorable reduction potential for 4a, as compared to 8.These results show that LAH can function as a one-electron donor toward geminal dichlorides.It was found that the diiodo analog 4b is more reactive toward LAH than 4a due to the inherent favorable reduction potentials of alkyl iodides compared to chlorides.The reactivity of 4b toward LAH was also found to be greater than that of the monoiodo analog (1b) in keeping with the more favorable reduction potential of the diiodide (4b) compared to the monoiodide (1b).The rates of cyclization of the corresponding haloalkyl radicals generated from 4a and 4b were also determined and were found to be 7.4E5/s for the chloroalkyl and 5.5E5/s for the iodoalkyl radical at 25 deg C.The formation of small amounts of the carbene-derived product, 5, in the reactions of both 4a and 4b with LAH appeared to be preceded by a radical intermediate.
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*.
Formation of Carbenes from Halo Carbon Radicals
Ashby, E. C.,Deshpande, Abhay K.,Doctorovich, Fabio
, p. 4205 - 4206 (2007/10/02)
The reactions of geminal alkyl dihalides with Me3Sn(1-), Ph2P(1-), and Mg* have been carried out and have been shown to produce carbene products that originate from halo carbon radical intermediates.
