Kinetic applications of electron paramagnetic resonance spectroscopy. 33. Diazirinyl radicals

Maeda, Yasuaki; Ingold, K. U.

doi:10.1021/ja00498a010

Cited by 26 publications

(16 citation statements)

References 6 publications

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“…The ligated boryl radicals were produced by hydrogen-atom abstraction from the corresponding ligated borane L-+BH,, using photochemically or thermally generated t-butoxyl radicals [equation ( 1)]." 8 In the spin-trapping experiments L -@ B H 3 + B u t O * -L-BH, + Bu'OH ( 1 ) with 2-methyl-2-nitrosopropane (MNP), 2,4,6-tri-t-butylnitrosobenzene (TBN), and phenyl-N-t-butylnitrone (PBN), the t-butoxyl radicals were generated by thermolysis of di-t-butyl hyponitrite (TBHN) in benzene solvent [equation (2)], whilst Naturally occurring boron consists of 80.8% ' 'B ( I 3/2) and 19.2% ' OB [ I 3; y(' 'B)/y(' ' B) 0.3351, but isotopically enriched ligated boranes containing 97.5 atom% 'B were often used to facilitate the interpretation of e.s.r. spectra.…”

Section: Resultsmentioning

confidence: 99%

Homolytic reactions of ligated boranes. Part 5. Spin-trapping and other addition reactions of ligated boryl radicals

Marti¹,

Roberts²

1986

J. Chem. Soc., Perkin Trans. 2

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The addition reactions of a variety of amine-and phosphine-boryl radicals (L+BH,; L = R, N or R,P) with 2-methyl -2-nitrosopropane (M N P), 2,4,6-tri-t-butylnitrosobenzene (TB N), and phenyl-N-t-butylnitrone (PBN) have been studied in benzene solution using e.s.r. spectroscopy. Spin-trapping of the boron-centred radicals b y M N P and PBN affords nitroxides, while addition of Me,N+BH, to the ambident TBN yields a mixture of the nitroxide and oxyaminyl adducts, with the latter predominating.Appropriately constituted amine-boryl radicals undergo p-N-C cleavage to give carbon-centred radicals in competition with their spin-trapping by M N P and PBN. In addition to providing mechanistic information, this competition has been used to measure the rate coefficient for spin-trapping of Prl,EtN+BH, by MNP. A t 31 4 K, ktrap is ca. 1.6 x 1 O8 dm3 mol-' s-l an$ thus amine-boryl radicals are trapped more efficiently than alkyl radicals. Attempts to scavenge H,N+BH, were frustrated by the rapid reduction of the spin-traps by ammonia-borane, but this amine-boryl radical did undergo ready addition t o alkyl cyanides and isocyanides, to 1,l -di-t-butylethylene, and to 2,6-di-t-butylpyridine as judged by e.s.r. spectroscopy. Addition t o cyanides affords transient iminyl radicals H,N+BH,( R)C=N' which undergo subsequent p-scission at a rate which increases along the series R = Et < Pr' < But in parallel with the stabilisation of the departing alkyl radical R'. Addition of carbon-centred radicals to unsaturated molecules is very import4nt in organicThe ligated boryl radicals R,N+BH, and R,P+BH, are isoelectrqnic with the substituted methyl radicals R,C-CH, and R,Si-CH,, respectively, and as part of a programme designed to explore the chemistry of the boron-centred radicals we have investigated their addition to a number of types of unsaturated molecule using e.s.r. spectroscopy.'Spin-trapping' of carbon-centred radicals by C-nitroso compounds and by nitrones, to give relatively persistent nitroxide adducts readily detectable by e.s.r. spectroscopy, has become established as an important tool in mechanistic free radical chemistry., Spin-trapping of ligated boryl radicals can provide similarly useful information, as we have indicated in a preliminary comm~nication,~ and here we describe this work in full. E.s.r. studies of the ad4ition reactions of the prototype amine-boryl radical ' H,N+BH, with nitriles, isocyanides, 1,ldi-t-butylethylene, and 2,6-di-t-butylpyridine are also reported.

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Section: Resultsmentioning

confidence: 99%

Homolytic reactions of ligated boranes. Part 5. Spin-trapping and other addition reactions of ligated boryl radicals

Marti¹,

Roberts²

1986

J. Chem. Soc., Perkin Trans. 2

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“…On the basis of the formation of nitriles and Nz, Maeda and Ingold postulated that the bimolecular selfreaction of diazirinyl radicals proceeds by way of an N-N a-dimer of type 4 ( Fig. 3A) (22). Once again, calculations show that the diazirinvl-radical 2'N is in the ' A, ground state and that the energy of the n*-n*-dimer 3'N is equal to that of the N-N o-dimer 4'N.…”

Section: Isolation Of a Benzene Valence Isomer With One-electron Phosmentioning

confidence: 99%

Isolation of a Benzene Valence Isomer with One-Electron Phosphorus-Phosphorus Bonds

Canac

Bourissou

Baceiredo

et al. 1998

Science

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“…This gave a complex mixture of more than ten compounds, among them 1 -chloro-2-dimethylaminocyclo-oct-5-ene (13) (19yo), a mixture of cisand trans-2-dimethylaminocyclo-oct-5-enol, (9) and ( 12) (32%), 7 and the anti-oxime of 2-dimethylaminocyclo-oct-5enone (14) (13%) * s 9 were identified. LAH Reduction of the crude product gave 5-dimethylaminocyclo-octene (16),' and compounds (9) and ( 12). The last two compounds were isolated as a 8 : 1 mixture.…”

Section: R2nh + Somentioning

confidence: 99%

“…were identified by g.c.-m.s. and peak matching: (i) 5-dimethylaminocyclo-octene l4 (15), 9.7 min, 5% ; m/e (%) 153 (M', 12), 138 (3), 125 (12), 124 (9), 110 (15), 84 (60), 71 (loo), 58 (12), 56 (27), 44 (18), and 42 (21); (ii) 8-dimethylamino-oct-4-en-1-01 (16) 11.9 min, 12% mle (%) 171 (M', lo), 140 (4), 126 (8), 84 (46), 71 (32), 58 (loo), 44 (24), and 42 (32); (iii) ( 9) and ( 12), 12.8 min, 26y0, m/e (%) 169 (M', 26) , 140 (14), 124 (8), 110 (22), 84 (59), 71 (loo), 58 (63), 56 (41), 44 (34), and 42 (37); (iv) unknown, 15.0 min, 5%. The mixture was chromatographed on silicic acid t o give two mixture fractions among others.…”

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confidence: 99%

Addition reactions of aminium radicals: synthetic studies of oxidative photoaddition of N-nitrodimethylamine (NNOD)

Chow¹,

Richard²

1982

J. Chem. Soc., Perkin Trans. 1

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Photoadditions of NNOD to various olefins under oxygen lead to 2-dimethylamino-1 -nitrate esters in good yields as primary products. The amino-nitrates are stable in acidic solution but their stability towards bases varies over a wide range depending on configuration. In most cases, the crude photoaddition products were reduced with lithium aluminium hydride to give good yields of the alcohols. The nitrates derived from cyclododeca-l,5,9-trienes were stable and reduced by lithium aluminium hydride to give, quite unexpectedly, the acyclic a,w-dimethylaminoalcohols. The oxidative photoaddition to cis,trans,trans-cyclododecatriene occurred preferentially at the transdouble bond and that to dicyclopentadiene at the norbornene double bond. In both cases, good regioselectivity was observed. The precursors to the nitrates were suggested to be the corresponding peroxynitrites which might also undergo various ionic or light-induced reactions. * Secondary reactions SCHEME 1 The reaction pattern of nitroamine photolysis * The details of chromatography are described in the thesis submitted by H. Richard.

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Kinetic applications of electron paramagnetic resonance spectroscopy. 33. Diazirinyl radicals

Cited by 26 publications

References 6 publications

Homolytic reactions of ligated boranes. Part 5. Spin-trapping and other addition reactions of ligated boryl radicals

Homolytic reactions of ligated boranes. Part 5. Spin-trapping and other addition reactions of ligated boryl radicals

Isolation of a Benzene Valence Isomer with One-Electron Phosphorus-Phosphorus Bonds

Addition reactions of aminium radicals: synthetic studies of oxidative photoaddition of N-nitrodimethylamine (NNOD)

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