1,2-Didehydroazepines from the photolysis of substituted aryl azides:  analysis of their chemical and physical properties by time-resolved spectroscopic methods

Li, Yu Zhuo; Kirby, John P.; George, Michael W.; Poliakoff, Martyn; Schuster, Gary B.

doi:10.1021/ja00232a022

Cited by 194 publications

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“…8) (Li et al, 1988;Soundararajan and Platz, 1990). Reaction with a nucleophile can then occur at a carbon atom adjacent to this nitrogen, specifically …”

Section: Chemistry Of the Reactionmentioning

confidence: 99%

Gln‐41 is intermolecularly cross‐linked to Lys‐113 in F‐actin by N‐(4‐azidobenzoyl)‐putrescine

Hegyi¹,

Michel²,

Shabanowitz³

et al. 1992

Protein Science

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The bifunctional reagent N-(4-azidobenzoyl)-putrescine was synthesized and covalently bound to rabbit skeletal muscle actin. The incorporation was mediated by guinea pig liver transglutaminase under conditions similar to those described by Takashi (1988, Biochemistry 27, 938-943); up to 0.5 M/M were incorporated into G-actin, whereas F-actin was refractory to incorporation. Peptide fractionation showed that at least 90% of the label was bound to Gln-41. The labeled G-actin was polymerized, and irradiation of the F-actin led to covalent intermolecular cross-linking. A cross-linked peptide complex was isolated from a tryptic digest of the cross-linked actin in which digestion was limited to arginine; sequence analysis as well as mass spectrometry indicated that the linked peptides contained residues 40-62 and residues 96-116, and that the actual cross-link was between Gln-41 and Lys-113. Thus the y-carboxyl group of Gln-41 must be within 10.7 A of the side chain (probably the amino group) of Lys-I13 in an adjacent actin monomer. In the atomic model for F-actin proposed by Holmes et al. (1990, Nuture 347, 44-49), the a-carbons of these residues in adjacent monomers along the two-start helices are sufficiently close to permit cross-linking of their side chains, and, pending atomic resolution of the side chains, the results presented here seem to support the proposed model.

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“…8) (Li et al, 1988;Soundararajan and Platz, 1990). Reaction with a nucleophile can then occur at a carbon atom adjacent to this nitrogen, specifically …”

Section: Chemistry Of the Reactionmentioning

confidence: 99%

Gln‐41 is intermolecularly cross‐linked to Lys‐113 in F‐actin by N‐(4‐azidobenzoyl)‐putrescine

Hegyi¹,

Michel²,

Shabanowitz³

et al. 1992

Protein Science

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“…This could be the reason why photolysis of p-azidoaniline (1) and p-azidodimethylaniline, unlike that of phenyl azide and most of its derivatives, gives only products of triplet nitrene reactions. 3,4 For instance, in the presence of oxygen at ambient temperature p-nitroaniline (2) and p-nitrosoaniline (3) are formed in quantitative yield upon photolysis of 1 (Scheme 1). 3,5 Since the early seventies it has been known that triplet arylnitrenes react with oxygen by formation of adducts.…”

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confidence: 99%

Matrix isolation and computational study of the photochemistry of p-azidoaniline

Pritchina

Gritsan

Bally

2006

Phys. Chem. Chem. Phys.

152

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The photochemistry of p-azidoaniline was studied in argon matrices in the absence and presence of oxygen. With the help of quantum chemical calculations we were able to characterize the triplet p-aminophenylnitrene as well as the cis-and trans-p-aminophenylnitroso oxides. It was found that the latter two isomers can be interconverted by selective irradiation and that they are ultimately converted into p-nitroaniline. Although restricted wavefunctions of the nitroso oxides are unstable, CASSCF calculations turned up no evidence for the claimed diradical character of these compounds. Also we found no evidence for dioxaziridines as intermediates of the conversion of the nitroso oxides to p-nitroaniline. IntroductionGreat progress has been made in understanding the photochemistry of aryl azides over the past few years. 1,2 Singlet phenylnitrene and a series of its simple derivatives have been detected directly and the effects of substituents on the spectra and the decay kinetics of singlet aryl nitrenes have been examined systematically. 2 Thereby it was found that groups which act as strong p donors dramatically accelerate the rate of intersystem crossing. This could be the reason why photolysis of p-azidoaniline (1) and p-azidodimethylaniline, unlike that of phenyl azide and most of its derivatives, gives only products of triplet nitrene reactions. 3,4 For instance, in the presence of oxygen at ambient temperature p-nitroaniline (2) and p-nitrosoaniline (3) are formed in quantitative yield upon photolysis of 1 (Scheme 1). 3,5 Since the early seventies it has been known that triplet arylnitrenes react with oxygen by formation of adducts. [5][6][7][8][9] In an early study on 1,4-diazidobenzene, two types of adducts (diamagnetic and paramagnetic) were detected in glassy matrices. 6 It was proposed that the diamagnetic adduct is an arylnitroso oxide, R-NQO 1 -O À , and the paramagnetic species is a ''spin isomer'' thereof, the triplet aryliminodioxy diradical, R-N-O -O . 6,10 Although subsequent studies did not confirm the formation of triplet adducts of arylnitrenes with oxygen, 3,5,7,8 speculations about the occurrence of aryliminodioxy diradicals in the photooxidation of aryl azides continue to surface occasionally in the literature. 11 This paper is devoted to a comprehensive experimental and computational study of the reactions of triplet arylnitrenes with oxygen in order to unambiguously identify the resulting adducts by their experimentally observed spectra, and to understand their properties. It should be noted that the earlier assignments of a strong near-UV absorption to arylnitroso oxides 3,5,7-9 were never supported by calculations. p-Azidoaniline was used in our matrix isolation study because, as noted above, it gives exclusively products of triplet nitrene reactions in solution, and we thought that this would also simplify the photochemistry in Ar matrices. In addition, the reaction of triplet p-aminophenylnitrene (4) with oxygen in solution and in glassy matrices has previously been studied. 5 2 Experim...

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“…Rather it is the ring expansion product, the didehydroazepine, that undergoes the bimolecular reaction (49). Didehydroazepine has a life time of about 10 s and reacts only with nucleophiles (50). Nucleophiles, such as amine, hydroxyl, thiol, and carboxy groups, are present in amino acid residues of lysine, arginine, histidine, serine, threonine, cysteine, glutamic acid, and aspartic acid.…”

Section: Discussionmentioning

confidence: 99%

Identification of Elements of the Peptide Binding Site of DnaK by Peptide Cross-linking

Zhang¹,

Walker²

1996

Journal of Biological Chemistry

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The DnaK protein of Escherichia coli (1) is a well characterized member of the family of highly conserved Hsp70 proteins (2) which play a variety of physiological roles by functioning as molecular chaperones (3). The Hsp70 family contains members whose expression is induced by a heat shock (Hsp70; heat shock protein 70 kDa) as well as members that are not induced by a heat shock (Hsc70; heat shock protein cognate 70 kDa). Along with at least 35 other proteins (4), the expression of DnaK is increased by a heat shock (5). Furthermore DnaK plays a negative role in regulating the E. coli heat shock response through the interaction with 32

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1,2-Didehydroazepines from the photolysis of substituted aryl azides: analysis of their chemical and physical properties by time-resolved spectroscopic methods

Cited by 194 publications

References 0 publications

Gln‐41 is intermolecularly cross‐linked to Lys‐113 in F‐actin by N‐(4‐azidobenzoyl)‐putrescine

Gln‐41 is intermolecularly cross‐linked to Lys‐113 in F‐actin by N‐(4‐azidobenzoyl)‐putrescine

Matrix isolation and computational study of the photochemistry of p-azidoaniline

Identification of Elements of the Peptide Binding Site of DnaK by Peptide Cross-linking

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