5026-76-6Relevant articles and documents
Cyclization of methyl-substituted 6-heptenyl radicals
Bailey, William F.,Longstaff, Sarah C.
, p. 2217 - 2219 (2007/10/03)
(Matrix presented) The behavior of a series of methyl-substituted 6-heptenyl radicals, generated from the corresponding iodides ((Me3Si)3SiH, AIBN in benzene at 80°C), has been investigated. The stereoselectivity of the 6-exo cyclizations, affording dimethylcyclohexanes, is low, and sizable quantities of methylcycloheptane, generated via 7-endo cyclization, are also produced.
Kinetics for the Reaction of a Secondary Alkyl Radical with Tri-n-butylgermanium Hydride and Calibration of a Secondary Alkyl Radical Clock Reaction
Lusztyk, J.,Maillard, B.,Deycard, S.,Lindsay, D. A.,Ingold, K. U.
, p. 3509 - 3514 (2007/10/02)
Arrhenius parameters for the reaction of a secondary alkyl radical with tri-n-butylgermanium hydride have been measured by using the cyclization of 1-methyl-5-hexenyl radical as a "clock" reaction.At 298 K the rate constant is 1.8*104 M-1s-1, which makes the secondary alkyl radical/n-Bu3GeH reaction about 80 times slower than the corresponding reaction with tri-n-butyltin hydride.The secondary alkyl radical clock reaction has been rather precisely calibrated by using new data and data from the literature.At attempt to carry out similar experiments with 1,1-dimethyl-5-hexenyl yielded much less precise data for the cyclization o f this tertiary alkyl radical.Reliable kinetic data for hydrogen abstraction from n-Bu3GeH by tertiary alkyl radicals could not be obtained by using either the parent bromide or appropriate N-hydroxypyridine-2-thione esters as alkyl radical sources.
Organometallic Reaction Mechanisms. 17. Nature of Alkyl Transfer in Reactions of Grignard Reagents with Ketones. Evidence for Radical Intermediates in the Formation of 1,2-Addition Product Involving Tertiary and Primary Grignard Reagents
Ashby, E. C.,Bowers, Joseph R.
, p. 2242 - 2250 (2007/10/02)
When a Grignard reagent reacts with an aromatic ketone, a radical anion-radical cation pair is formed which can collapse to give 1,2-addition product or dissociate to form a radical anion and a free radical within the solvent cage which in turn can collapse to 1,2-addition product or a conjugate addition product or escape the solvent cage to form pinacol.The 1,2-addition products, which form after dissociation of the radical anion-radical cation pair, show free-radical character as indicated by the cyclized 1,2-addition products formed from the reaction of a tertiary Grignard reagent probe with benzophenone in THF and from the reaction of a primary Grignard reagent probe (neooctenyl Grignard reagent) with benzophenone in ether.The 1,6-addition products, which come about after dissociation of the radical anion-radical cation pair, show free-radical character as evidenced by the cyclized 1,6-addition products formed in all of the reactions which involve the tertiary probe Grignard reagent (in all solvents studied) with benzophenone and 2-MBP and also in the reaction of the neooctenyl probe Grignard reagent with 2-MBP.
