128885-82-5Relevant academic research and scientific papers
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 (1994)
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*.
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
Ashby, E. C.,Desphande, Abhay K.
, p. 4530 - 4535 (1995)
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.
The Mechanism of Reaction of Geminal Dihalides with Sodium Trimethyltin. Evidence for a Single Electron Transfer Initiated Reaction Which Produces Both Radical and Carbene Intermediates
Ashby, E. C.,Deshpande, Abhay K.
, p. 7358 - 7366 (1994)
The reactions of two geminal dihalides, 6,6-dichloro-5,5-dimethyl-1-hexene (2a) and 6,6-diiodo-5,5-dimethyl-1-hexene (2b) with sodium trimethyltin (NaSnMe3), a known one-electron donor toward alkyl halides, have been studied.Evidence for a single electron transfer (SET) pathway has been obtained for both reactions.Although the monochloro analog of 2a, namely 7, was inert toward NaSnMe3, 2a afforded 11 products.The nature of the products clearly indicates that the presence of two chlorine atoms on the same carbon atom results in a more favorable reduction potential than when just one chlorine atom is present.Both 2a and 2b on reaction with NaSnMe3 also produced carbene-derived products, and evidence is presented that establishes that the carbene intermediate was in fact preceded by a radical intermediate.In addition, trimethyltin-substituted products (open chain as well as cyclized) were also obtained from both substrates and were found to be derived from radical intermediates.
Formation of Carbenes from Halo Carbon Radicals
Ashby, E. C.,Deshpande, Abhay K.,Doctorovich, Fabio
, p. 4205 - 4206 (1993)
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.
Competing Radical, Carbanion, and Carbene Pathways in the Reactions of Hindered Primary Alkyl Halides with Lithium Dialkylamides
Ashby, E. C.,Park, B.,Patil, G. S.,Gadru, K.,Gurumurthy, R.
, p. 424 - 437 (2007/10/02)
A variety of methods were utilized to study the mechanism of reaction of 6-iodo-5,5-dimethyl-1-hexene and its bromo, chloro, and tosylate derivatives with LDA and several other lithium dialkylamides.In the reaction of 6-iodo-5,5-dimethyl-1-hexene with LDA in THF, radical, carbanion, and carbene pathways occured simultaneously.However, when the corresponding bromide was allowed to react with LDA, the radical pathway was minor and when the corresponding chloride or tosylate was allowed to react with LDA, no evidence for radical products was observed.This is the first time that competing radical, carbanion, and carbene pathways have been detected in the reaction of a primary alkyl halide with any nucleophile.
