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.
Rate Constants and Arrhenius Parameters for the Reactions of Some Carbon-Centered Radicals with Tris(trimethylsilyl)silane
Chatgilialoglu, C.,Dickhaut, J.,Giese, B.
, p. 6399 - 6403 (2007/10/02)
Rate constants for the reactions of some carbon-centered radicals with (Me3Si)3SiH have been measured over a range of temperatures by using competing unimolecular radical reactions as timing devices.For example, the rate constants (at 298 K) are 3.7, 1.4, and 2.6 x 1E5 M-1 s-1 from primary, secondary, and tertiary alkyl radicals, respectively.Comparison of the radical trapping abilities of tri-n-butylstannane and tris(trimethylsilyl)silane is discussed.The use of 1,1-dimethyl-5-hexenyl cyclization as a radical clock has been recalibrated by using new data and data from the literature.
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.
EVIDENCE FOR A SINGLE ELECTRON TRANSFER MECHANISM IN REACTIONS OF LITHIUM DIORGANOCUPRATES WITH ORGANIC HALIDES
Ashby, E. C.,DePriest, R. N.,Tuncay, A.,Srivastava, Sushil
, p. 5251 - 5254 (2007/10/02)
It has been demonstrated by means of spectroscopic studies involving cyclizable alkyl halides that lithium dimethylcuprate can react with organic halides by a single electron transfer pathway.
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.
SELECTIVE REDUCTION OF TERTIARY ALKYL, BENZYL, AND ALLYL HALIDES TO HYDROCARBONS USING LITHIUM 9,9-DI-N-BUTYL-9-BORABICYCLONONANATE
Toi, Hiroo,Yamamoto, Yoshinori,Sonoda, Akio,Murahashi, Shun-Ichi
, p. 2261 - 2268 (2007/10/02)
The title 9-borabicyclononane(9-BBN) ate complex (1) brings about selective removal of tertiary alkyl, benzyl, and allyl halides to give the corresponding hydrocarbons in excellent yields without concomitant attack on secondary, primary and aryl derivatives.The reduction of cis- and trans-4-t-butyl-1-methylcyclohexyl chlorides (2) with 1 gives 4-t-butyl-1-methylcyclohexanes (3) with partial inversion of configuration in cyclohexane, while that in benzene gives thermodynamically trans-3 predominantly.The reactions of 1,1-dimethyl-5-hexenyl chloride (4) and 1,7,7-trimethylbicyclohept-2-yl chloride (8) with 1 proceed with the rearrangements characteristic to a carbonium ion intermediate.The reduction of 1-ethyl-1-methylpentyl chloride with 1 follows a second-order rate equation.
