Buten-4-yl radical

In the hydroxylahon of cyclopropyl probes, the cyclopropylcarbinyl radical clock can either rearrange to ring-opened 3-buten-l-yl radical before being trapped or rebound with the hydroxyl carrier to yield the alcohol product direchy (Scheme... 

For example, disproportionation of but-2-yl radicals produces a mixture of butenes as shown (Scheme 1.1 I).138 Thermodynamic considerations suggest thai but-l-ene and but-2-enes should be formed in a ratio of ca 2 98. However, the observed 5 4 ratio of but-1-ene but-2-enes is little different from the 3 2 ratio that is expected on statistical grounds (i.e. ratio of f5-hydrogens in the I- and 3-positions). 

The olefin 3,3-dimethyl-l-butene (III) was studied since it gave almost exclusively the expected product 3,3-dimethyl-l-buten-2-yl acetate (VII) with only traces of ketone or 3,3-dimethyl-l-buten-l-yl acetate. With a single product the test of material balance was simplified since it was possible to run a blank on the wet separation and then check the yield of VII by isotope dilution using (CH3)3CC(OCOCD3)=CH2. Experiments with III are not complicated by isomerization or allylic palladium complex formation and are unlikely to involve free radical reactions. 

Bond formation between the radicals 143 and 145 with 150 offers an explanation for the formation of the 2-methyl-( )-3-[3(8),6-m-menthadien-6-yl]-2-buten-l-yl ligands in 139 and 142. Loss of CO and / -elimination in 150 leads to 151, which forms the j3-2-methyl-( )-3-[3(8),6-w-menthadien-6-yl]-... 

The 3-exo cychsation of ester-substituted 3-butenyl radicals is important in the rearrangement of 2-methyleneglutamate to 3-methyl itaconate catalysed by a-methyleneglutamate mutase. Newcomb and co-workers have applied laser flash photolysis to cleverly designed precursors to show that an ester group at the 1-position of 3-buten-l-yl accelerates the 3-exo cychsation by a factor of about 3, but that the same substituent at the 3-position slows the process by a factor of about 50 [45]. 

Theoretical thermochemistry of the l-buten-3-yn-l-yl radical and its chloro derivative s ... 

Diethoxyphosphinyl-2-buten-4-olide reacts with lithiated dithianes followed by an intermolecular Wittig-Homer reaction to produce fused 7-lactones (equation 37). The reaction of 2-lithio-l,3-di-thianes with nitroarenes gives 2- or 4-[(l,3-dithian)-2 -yl]cyclohexa-3,S(or 2,S-)-diene-l-nitronate compounds (conjugate addition products), free nitroarene radical anions (redox products), 1,3-dithianes and 2,2 -bis( 1,3-dithianes). ... 

Hamill, Guarino, and Ronayne (II) gamma irradiated 0.18 mole % benzyl chloride in glassy 2-methyltetrahydrofuran (MTHF) at liquid nitrogen temperature and obtained a maximum ultraviolet absorption band at 320 m/x in agreement with Porter and Strachan, see Table I. They also irradiated 1.0 mole % allyl chloride, allyl bromide and allyl alcohol in 3-methylpentane (3-MP) and in all cases observed a maximum absorption band at 228 m/x which they attributed to the allyl free radical. They also irradiated 3-chloro-1-butene and 3-chlorocyclohexene in 3-MP and determined the wavelengths of the absorption band maxima of the 1-methyl allyl and 2-cyclohexen-l-yl free radicals given in Table I. 

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