- Radical and Nitrenoid Reactivity of 3-Halo-3-phenyldiazirines
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3-Halo-3-phenyl-3H-diazirines (halogen = Br or Cl) undergo a dissociative single-electron transfer from alkyllithiums (RLi) in THF-based solvent mixtures. The resulting 3-phenyldiazirinyl radical, observed by EPR spectroscopy, is eventually transformed to benzonitrile. In Et2O, 2 equiv of RLi add to both nitrogens of halodiazirine N=N bond, affording N,N′-dialkylbenzamidines. The nitrenoid reactivity of some N-alkyl-1H-diazirine intermediates is manifested by their insertion into the α-C-H bond of THF or Et2O.
- Navrátil, Rafael,Tarábek, Ján,Linhart, Igor,Martin?, Tomá?
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supporting information
p. 3734 - 3737
(2016/08/16)
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- Dimerization and trapping of diazirinyl radicals
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Computational and experimental methods have been utilized to examine the facile dimerization of diazirinyl radicals. Two potential dimers were investigated using density functional theory. Both were shown to have low-barrier reaction coordinates leading t
- Thompson, Robert A.,Francisco, Joseph S.,Grutzner, John B.
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p. 756 - 765
(2007/10/03)
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- A facile one-pot conversion of non-enolizable aldehydes to diazirines
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A general route to monoalkyl diazirines from non-enolizable aldehydes through N-trimethylsilyl diaziridines is described. (C) 2000 Elsevier Science Ltd.
- Likhotvorik, Igor R.,Tae, Eunju Lee,Ventre, Celine,Platz, Matthew S.
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p. 795 - 796
(2007/10/03)
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- Reactions and reactivity of acyloxycarbenes
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Phenylacetoxycarbene, phenyl(pivaloyloxy)carbene, and phenyl(benzoyloxy)carbene, photolytically generated from diazirine precursors in pentane at 25°C, efficiently rearranged by 1,2-acyl migrations to give high yields of the appropriate 1,2-diketones. The kinetics of these rearrangements were determined by laser flash photolysis. Substituent effects on the acyl migrations and ab initio electronic structure calculations on ground state carbenes and transition states were employed to analyze the rearrangement mechanism. Additions of phenylacetoxycarbene to alkenes proceeded in good yields, in lieu of the 1,2-acyl shift; absolute rate constants were obtained for these reactions of the ambiphilic carbene. (Phenoxymethyl)acetoxycarbene gave only a 1,2-H shift; the potentially competitive 1,2-acetyl migration was suppressed.
- Moss, Robert A.,Xue, Song,Liu, Weiguo,Krogh-Jespersen, Karsten
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p. 12588 - 12597
(2007/10/03)
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- 1,2,4,6-CYCLOHEPTATETRAENE: THE KEY INTERMEDIATE IN ARYLCARBENE INTERCONVERSIONS AND RELATED C7H6 REARRANGEMENTS
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Thermolysis or photolysis of phenyldiazomethane (2) produces phenylmethylene (3), which ring-expands to give 1,2,4,6-cycloheptatetraene (6).Spectroscopic and chemical evidence rule out bicyclo(4.1.0)hepta-2,4,6-triene (4), cycloheptatrienylidene (5), and bicyclo(3.2.0)hepta-1,3,6-triene (11) intermediates.The strained allene in cycloheptatetraene (6) exhibits infrared absorption at 1824 and 1816 cm-1.Deuterium substitution produces the expected 10-cm-1 shift in the allene absorption.Fluorine or chlorine substitution substantially enhances the allene absorption intensity.Deuterium labeling studies reveal that the intramolecular chemistry of cycloheptatetraene (6) involves reversible thermal or photochemical equilibriation with phenylmethylene (3).The intermolecular chemistry of 6 involves dimerization.At temperatures as low as 10 K, 6 forms a labile (2+2) dimer,7, which undergoes thermally allowed, electrocyclic ring opening to give heptafulvalene (8) upon warming to room temperature.The rearrangements of 7-acetoxynorbornadiene (9), 2-diazobicyclo(3.2.0)hepta-3,6-diene (31), and 8-diazobicyclo(2.2.2)octa-2,5-dien-7-one (33) all involve cycloheptatetraene (6) intermediates.
- McMahon, Robert J.,Abelt, Christopher J.,Chapman, Orville L.,Johnson, Jeffery W.,Kreil, Curits L.,et al.
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p. 2456 - 2469
(2007/10/02)
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