Novel synthesis of vinyl ethers induced by carbon–halogen bond homolysis

Cook, Michelle M.; Hares, O.; Johns, Amanda; Murphy, John A.; Patterson, Christopher

doi:10.1039/c39860001419

Cited by 15 publications

(5 citation statements)

References 1 publication

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“…C–C bond cleavage of epoxy carbinyl radicals is also known but only if the substrate has radical-stabilizing groups, e.g., phenyl or vinyl. [29, 30] Ab initio molecular orbital calculations on a simple epoxy carbinyl radical model suggest that C–O bond cleavage is dominant in alkyl-substituted epoxy carbinyl radicals (Fig. 3).…”

Section: Introductionmentioning

confidence: 99%

Fragmentation of a linoleate-derived γ-hydroperoxy-α,β-unsaturated epoxide to γ-hydroxy- and γ-oxo-alkenals involves a unique pseudo-symmetrical diepoxycarbinyl radical

Salomon

2012

Free Radical Biology and Medicine

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Many of the pathological effects of lipid peroxidation are mediated by aldehydes generated through fragmentation of lipid peroxides. Among these aldehydes, the γ-hydroxy- and γ-oxo-α,β-alkenals, e.g., 4-hydroxy-2-nonenal (HNE), and 4-oxo-2-nonenal (ONE), are especially prone to modify proteins and DNA through covalent adduction. In addition the “mirror image” γ-hydroxy- and γ-oxo- α,β-alkenal phospholipids, can serve as high affinity ligands for biological receptors triggering pathology. Therefore, the mechanisms by which these aldehydes are generated in vivo are under intense scrutiny. We now report observations supporting the intermediacy of a unique pseudo symmetrical diepoxycarbinyl radical that accounts for the coproduction of HNE, ONE and their “mirror image” analogues 9-hydroxy-12-oxo-dodec-10-enoic acid (HODA), 9-keto-12-oxo-dodec-10-enoic acid (KODA) upon fragmentation of 13-hydroperoxy-cis-9,10-epoxyoctadeca-11-enoic acid (13-HP-Epo-Acid).

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Section: Introductionmentioning

confidence: 99%

Fragmentation of a linoleate-derived γ-hydroperoxy-α,β-unsaturated epoxide to γ-hydroxy- and γ-oxo-alkenals involves a unique pseudo-symmetrical diepoxycarbinyl radical

Salomon

2012

Free Radical Biology and Medicine

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“…Experimentally, the ring opening of substituted oxiranylmethyl radicals occurs with the exclusive formation of the corresponding allyloxy radical by C−O bond cleavage of the oxirane ring (eq 1), except when aryl substituted at C 3 of the oxiranylmethyl radical system have provided an upper limit for the rate of ring opening of the oxiranylmethyl radical of ∼10 8 s -1 , while the competitive fragmentation of the oxiranylmethyl portion versus the that of the cyclopropylmethyl portion in the cyclopropyloxiranylmethyl radical has provided an upper limit for the rate of ring opening of the oxiranylmethyl radical of ∼10 10 s -1 …”

Section: Introductionmentioning

confidence: 99%

Ab Initio Theoretical Studies on the Ring-Opening Modes of the Oxiranyl-, Aziridinyl-, Oxaziridinyl-, and Thiaranylmethyl Radical Systems

Pasto

1996

J. Org. Chem.

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Ab initio theoretical studies have been carried out on the oxiranyl-, aziridinyl-, oxaziridinyl-, and thiaranylmethyl radical systems and on the various possible conformations of the ring-opened heteroallyllic radical systems derived by ring opening of the first three systems. Previous theoretical studies on the ring opening of the oxiranylmethyl radical indicated that there is an overwhelming thermodynamic preference for the formation of the allyloxy radical over the formation of the (vinyloxy)methyl radical. The results of the present theoretical studies on the potential energy surfaces for ring opening also indicate a strong kinetic preference for allyloxy radical formation over the formation of the (vinyloxy)methyl radical. The results of the present calculations on the aziridinylmethyl radical indicates that it kinetically prefers to ring open by cleavage of the C-N bond, but thermodynamically by cleavage of the C-C bond. The results of the calculations on the C 2 H 4 NO radical system indicate that ring opening of the oxaziridinylmethyl radical by C-O bond cleavage is both thermodynamically and kinetically favored over C-N bond cleavage. Calculations on the thiaranylmethyl radical suggest that it does not represent a minimum-energy structure on the C 3 H 5 S potential energy surface.

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“…585, t R 10.80 min, 2-methylcyclooctanone 26c, m/z 111 (96%), 97 (76), 83 (35), 67 (33), 55 (80), 41 (100), 27 (78); peak no. 559, t R 10.90 min, non-1-en-3-one 23c, m/z 111 (17%), 97 (15), 83 (57), 70 (38), 55 (75), 41 (62), 27 (62); peak no. 591, t R 11.1 min, 1-vinylcyclononanol 21c m/z 140 (2%), 138 (7), 109 (17), 94 (19), 81 (22), 79 (30), 70 (33), 67 (96), 56 (38), 55 (64), 43 (39), 41 (100), 39 (78); peak no.…”

Section: Reaction Of 2-bromomethyl-1-oxaspiro[26]nonane 12c With Trib...mentioning

confidence: 99%

“…An intriguing cascade sequence incorporating three of these homolytic steps is outlined in Scheme 1. Simple epoxymethyl radicals related to radical 2 are known to undergo very rapid β-scissions 13, 14 of their carbon-oxygen bonds 7, 15 and hence 1-vinylcycloalkoxyl radicals 3 should form with great ease. Intermediate 3 is expected to undergo a second β-scission, at moderate temperature, to selectively afford the more stabilised 3-oxoalkenyl radical 4, in preference to scission of the vinyl-carbon bond.…”

Section: Introductionmentioning

confidence: 99%

Cascade rearrangement of spiroepoxymethyl radicals into 2-oxocycloalkyl radicals: evaluation of a two-carbon cycloalkanone ring expansion

Afzal¹,

Walton²

1999

J. Chem. Soc., Perkin Trans. 2

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Series of 2-bromomethyl-and 2-hydroxymethyl-1-oxaspiro[2.n]alkanes were prepared from cycloalkanones by initial Wadsworth-Horner-Emmons methodology to afford ester-substituted methylenecycloalkanes. The latter were selectively reduced to hydroxymethylmethylenecycloalkanes which were epoxidised with peroxyacetic acid. Homolytic reactions were studied by EPR spectroscopy which enabled transient 3-oxoalk-1-enyl radicals, and their cyclisation products, 2-oxocycloalkyl and 2-oxocycloalkylmethyl radicals, to be characterised. This evidence, together with end product analyses of organotin hydride reductions of the 2-bromomethyl-1-oxaspiro[2.n]alkanes, established that the initial spiroepoxymethyl radicals rearranged by a three-stage cascade of two consecutive β-scissions followed by a cyclisation. Cyclisations of the 3-oxoalk-1-enyl radicals took place mainly in the endo-mode to afford 2-oxocycloalkyl radicals, except for the 5-oxohept-6-enyl radical for which exo-cyclisation to generate the 2-oxocyclohexylmethyl radical was preferred. Kinetic data for the exo-and endo-cyclisations of the 4-oxohex-5-enyl radical were obtained from tributyltin hydride mediated reactions of 2-bromomethyl-1-oxaspiro[2.3]hexane.

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Novel synthesis of vinyl ethers induced by carbon–halogen bond homolysis

Cited by 15 publications

References 1 publication

Fragmentation of a linoleate-derived γ-hydroperoxy-α,β-unsaturated epoxide to γ-hydroxy- and γ-oxo-alkenals involves a unique pseudo-symmetrical diepoxycarbinyl radical

Fragmentation of a linoleate-derived γ-hydroperoxy-α,β-unsaturated epoxide to γ-hydroxy- and γ-oxo-alkenals involves a unique pseudo-symmetrical diepoxycarbinyl radical

Ab Initio Theoretical Studies on the Ring-Opening Modes of the Oxiranyl-, Aziridinyl-, Oxaziridinyl-, and Thiaranylmethyl Radical Systems

Cascade rearrangement of spiroepoxymethyl radicals into 2-oxocycloalkyl radicals: evaluation of a two-carbon cycloalkanone ring expansion

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