ライフサイエンスコーパス: nitrene

1 to the formation of the closed-shell singlet nitrene.

2 The S(1) state decays to produce the singlet nitrene.

3 dride transfer to the rhodium-complexed acyl nitrene.

4 ene N-oxide intermediates as well as triplet nitrene.

5 sed as the tether between the alkene and the nitrene.

6 stepwise Curtius rearrangement via the free nitrene.

7 riplet energy transfer to form triplet alkyl nitrene.

8 of the singlet from the lower-energy triplet nitrene.

9 evidence of a tunneling reaction involving a nitrene.

10 ucts from the conversion of azido ligands to nitrenes.

11 hed light on the electronic structure of the nitrenes.

12 lower energy singlet state for each of these nitrenes.

13 orption spectra of the corresponding singlet nitrenes.

14 nitrenes relax to the corresponding triplet nitrenes.

15 formation of the corresponding triplet alkyl nitrenes (1-n), via intramolecular energy transfer from

16 trene radical cation, (pi*)(4)(delta*)(2)(pi(nitrene,1))(1)(pi(nitrene,2))(0).

17 ated triplet nitrene, (pi*)(4)(delta*)(1)(pi(nitrene,1))(1)(pi(nitrene,2))(1).

18 1f), which serves as a reservoir for singlet nitrene 1b.

19 More specifically, nitrene 2 does undergo alpha-photocleavage to form benzo

20 The secondary photolysis of nitrenes 2 is further supported with molecular modeling

21 eads to selective formation of triplet alkyl nitrenes 2 that were detected directly with laser flash

22 Nitrenes 2 were further characterized with argon matrix

23 t benzoyl radicals 3 can also be formed from nitrenes 2.

24 on, (pi*)(4)(delta*)(2)(pi(nitrene,1))(1)(pi(nitrene,2))(0).

25 ne, (pi*)(4)(delta*)(1)(pi(nitrene,1))(1)(pi(nitrene,2))(1).

26 The thermally generated nitrene 23 is observed directly by matrix-isolation ESR

27 sient absorption spectra due to formation of nitrene 2a (lambdamax=320 nm) and benzoyl radical 3a (la

28 ay of 3a is 2 x 105 s-1 in methanol, whereas nitrene 2a decays with a rate of approximately 91 s-1.

29 In a hydrophobic environment singlet nitrene 2a partitions between forming triplet nitrene 3a

30 Nitrene 2a, with an n,pi* configuration as the lowest tr

31 none (1b) releases the corresponding singlet nitrenes 2a and 2b.

32 om recombination of benzoyl radicals 3a with nitrenes 2a.

33 Singlet nitrene 2b reacts with the unactivated CH bonds of cyclo

34 The lifetime of nitrene 2b was measured to be 16 ms.

35 sis of tetrafluoro azide 1b releases singlet nitrene 2b, which has a lifetime of 172 ns in benzene an

36 in azide 1b leads to energy transfer to form nitrene 2b; however, alpha-cleavage is not observed sinc

37 to the lower-energy and longer-lived triplet nitrene (3)(2-NpSO(2)N).

38 itrene 2a partitions between forming triplet nitrene 3a and an acyl-substituted didehydroazepine 4a,

39 s, respectively) to the lower energy triplet nitrenes 3a and 3b, intermediates which do not react to

40 and 525-527, positioning the photogenerated nitrene a maximum of 19-26 A from the complemented rRNA

41 Regeneration of the nitrene active species by reaction of ArN3 with the meta

42 y exothermic reactions with ArN3 to form the nitrene active species.

43 re formed by copper-catalyzed intramolecular nitrene addition to alkenes.

44 traction from substrate C-H bonds or initial nitrene-addition to one of the olefinic carbons.

45 n, (3) alkene and alkyne polymerization, (4) nitrene and carbene group transfer, (5) fundamental tran

46 extremely slow thermal reaction between the nitrene and O2 was observed, whereas at higher temperatu

47 s an extremely valuable method of generating nitrenes and studying their thermal rearrangements.

48 ittings of more than 20 substituted aromatic nitrenes and the radical stabilizing ability of the arom

49 between the singlet and triplet state of the nitrene, and oxygen quenching experiments suggest that t

50 long that N-N coordinate to form the singlet nitrene, and with a barrier of only approximately 5 kcal

51 ition metal-catalyzed transfers of carbenes, nitrenes, and oxenes are powerful methods for functional

52 Nitrene- and carbene-generating photolinkers were invest

53 The closed-shell singlet and triplet nitrene are separated by a small energy gap in protic so

54 The products from these two nitrenes are derived from the corresponding singlet nitr

55 doyl, boryl, silyl, phosphonyl, and sulfonyl nitrenes are included.

56 n-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive eliminat

57 The triplet nitrenes are persistent at 77 K and their spectra were r

58 The triplet alkyl nitrenes are persistent intermediates that do not abstra

59 , indicating that singlet states of aromatic nitrenes are preferentially stabilized by radical stabil

60 ational spectra of the corresponding triplet nitrenes, azirines, and didehydroazepines were observed,

61 bond-forming/-reduction sequences as well as nitrene-based C-H amination methods.

62 which ensures formation of the triplet alkyl nitrene by bypassing the singlet nitrene intermediate.

63 ell as the corresponding singlet and triplet nitrenes by CBS-QB3 and B3LYP computational methods.

64 and aminations via high-valent iron oxos and nitrenes, C(sp(3))-H alkylations via isoelectronic iron

65 The nitrenes can in many cases be isolated in low-temperatur

66 ixth ligand bound to cobalt(III) in the mono-nitrene case remains elusive, but some plausible candida

67 nor (4b)) without evidence of imidyl or free nitrene character.

68 corresponding oxadiazole, is the predominant nitrene chemistry, occurring on the time scale of a few

69 zidopyridine 1-oxide is dominated by triplet nitrene chemistry.

70 mu-N(t)Bu) (3) demonstrate that the terminal nitrene [Cl2NN]Cu horizontal lineN(t)Bu is the active in

71 hesis show a greater tendency toward triplet nitrene complexes and hence the potential for metal-free

72 Terminal copper- and silver-nitrene complexes have long been proposed to be the key

73 Metal-mediated decomposition to form nitrene complexes is investigated by using DFT for proto

74 trongly suggest the intermediacy of reactive nitrene complexes of the type [SiP(iPr)(3)]Fe(NAr) that

75 ing bridging and terminal copper- and silver-nitrene complexes, which are characterized by NMR spectr

76 nitrene nor the subsequently formed triplet nitrene contribute to cross-link formation.

77 Dicopper nitrenes [Cu]2(mu-NCHRR') derived from 1 degrees and 2 d

78 fluorinated azide 1b can form useful singlet nitrene derived adducts upon photolysis.

79 enching experiments suggest that the triplet nitrene derives from the triplet excited state of the su

80 e a highly electrophilic intermediate as the nitrene donor and a symmetrical aziridine-like transitio

81 s are derived from the corresponding singlet nitrene, either directly or via thermal repopulation of

82 Direct observation of the triplet nitrene, energetic differences between the singlet and t

83 henyl, the contribution of the nitrosamine/O-nitrene-forming pathway was diminished.

84 We report a metathesis reaction in which a nitrene fragment from an isocyanide ligand is exchanged

85 rom an isocyanide ligand is exchanged with a nitrene fragment of an imido ligand in a series of niobi

86 sts because they serve as a useful source of nitrene fragments and interesting nitrene rearrangement

87 ce signal by using CL-activated formation of nitrenes from azides to locally fix a fluorescent probe

88 he spin-selective photogeneration of triplet nitrenes from azidoformates.

89 Thermally persistent triplet sulfonyl nitrene, FSO(2)N, was produced in the gas phase in high

90 eivably lacks sufficient reactivity with the nitrene generated from the probe.

91 The nitrene generation from azide 5 occurs on the S(2) surfa

92 nal nitrenes [(i) Pr2 NN]Cu=NAr that undergo nitrene group transfer to PMe3 , (t) BuNC, and even into

93 mido complex that can engage in simultaneous nitrene-group transfer and oxygen-atom transfer to gener

94 d phenyl isocyanate, causing sulfur-atom and nitrene-group transfer, respectively.

95 he slippery potential energy surface of aryl nitrenes has revealed unexpected and fascinating reactio

96 lnitrene RS(O)N, a highly reactive alpha-oxo nitrene, has been rarely investigated.

97 otolysis of 1 reveals that the triplet alkyl nitrenes have absorption around 300 nm.

98 In contrast, nonmetallic nitrenes have so far only been spectroscopically observe

99 4 and 8 to be "masked" forms of the terminal nitrenes [(i) Pr2 NN]Cu=NAr that undergo nitrene group t

100 with bulkier azides N3 Ar leads to terminal nitrenes [(i) Pr2 NN]Cu]=NAr that dimerize via formation

101 es intersystem crossing (ISC) to the triplet nitrene in aprotic and protic solvents as well as proton

102 FVT of the azide produces the nitrene in high yield and with only minor contaminations

103 ions equal the rates of decay of the singlet nitrenes in 88% formic acid and are as follows: p-biphen

104 report the first detection of triplet alkyl nitrenes in fluid solution by laser flash photolysis of

105 Nitrenes included within octa acid attack one of the fou

106 Transition-metal-catalyzed C-H amination via nitrene insertion allows the direct transformation of a

107 roducts are formed via a rare intramolecular nitrene insertion into an adjacent methoxy C-H bond foll

108 dines via dirhodium catalyzed intramolecular nitrene insertion into sp(3) C-H bonds.

109 ct to improve the efficiency of a late-stage nitrene insertion reaction.

110 ed us to characterize the C-N stretch of the nitrene intermediate at 1201 cm(-)(1).

111 earrangement versus the loss of N2 to form a nitrene intermediate provides strong evidence that the c

112 recently, the Lewis acid adduct of a copper-nitrene intermediate was trapped at -90 degrees C and sh

113 iplet alkyl nitrene by bypassing the singlet nitrene intermediate.

114 Nitrene intermediates 2N_L and 3N_L are also examined by

115 Iron imide/nitrene intermediates [Fe(qpy)(NR)(X)](n+) (CX, X = NR,

116 The triplet alkyl nitrene intermediates are also trapped with molecular ox

117 electronic structure of the proposed copper-nitrene intermediates has also been controversially disc

118 The electronic structures of these putative nitrene intermediates have been examined by DFT methods.

119 High-valent copper-nitrene intermediates have long been proposed to play a

120 amination is hypothesized to proceed via Rh2-nitrene intermediates in either the Rh2(II,II) or Rh2(II

121 ns but selectively yields only triplet alkyl nitrene intermediates that dimerize to form 3b.

122 ngement of allylic hydrazides, via singlet N-nitrene intermediates, is reported.

123 involves the insertion of metal carbenes and nitrenes into C-H bonds.

124 The resulting nitrene is a powerful base and abstracts protons extreme

125 2N_L and 3N_L are also examined by DFT (the nitrene is an NSO3R species).

126 are in the interior of the cavity where the nitrene is generated, and in CB7 they are at the exterio

127 A nitrene is likely the aminating species responsible for

128 cis-4-octene suggest that reactivity of the nitrene is mainly through the singlet channel, despite a

129 ions 2252-2253, such that the photogenerated nitrene is maximally 17-19 A from 23S RNA nucleotides G2

130 rted process is only 27 kcal/mol, and a free nitrene is not produced upon pyrolysis of acetyl azide.

131 products that are frequently observed if the nitrene is produced by photolysis.

132 ead, we favor a mechanism in which free aryl nitrene is released during the catalytic cycle and combi

133 The singlet nitrene is too short-lived to be observed and, thus, to

134 reaction, in which an electrophilic rhodium nitrene is trapped by an alkyne, resulting in the format

135 bility of the closed-shell singlet states in nitrenes is shown by Natural Resonance Theory to be very

136 inodimethane, and not the singlet or triplet nitrene, is the pivotal reactive intermediate involved i

137 of nearby singlet and triplet states of the nitrene itself.

138 Each specific EPI-nitrene-modified site involved either Tyr195 of loop C o

139 ido complex was effective for delivering the nitrene moiety to both C-H bond substrates (42% yield) a

140 itrene radical species is able to transfer a nitrene moiety to phosphines and abstract a hydrogen ato

141 intramolecular one-electron transfer to the "nitrene" moiety, but now from the porphyrin ring instead

142 ansfer from the cobalt(II) porphyrin to the 'nitrene' moiety (Ns: R'' = -SO2-p-C6H5NO2; Ts: R'' = -SO

143 stabilizes the triplet state of the carbonyl nitrene more than the corresponding singlet state.

144 ally unstable and decomposed to form triplet nitrenes NCN and NNC as well as triplet carbenes NCCCN,

145 o the imine is a concerted process without a nitrene/nitrenoid intermediate.

146 Neither the initially produced singlet nitrene nor the subsequently formed triplet nitrene cont

147 ate has the shortest lifetime of any singlet nitrene observed to date and is a true reactive intermed

148 t the viability of organic cycloadditions of nitrenes onto the diamond (100) surface.

149 bonds is to insert a monovalent N fragment (nitrene or nitrenoid) into a C-H bond or add it directly

150 Our findings suggest that an Rh-nitrene oxidant can react with hydrocarbon substrates th

151 chanical calculations suggest a plausible Rh-nitrene pathway.

152 Concomitantly, the nitrene PhNBN is formed via phenyl rearrangement.

153 One EPI-nitrene photoactivated molecule was incorporated in each

154 3N is Rh2(II,III) with a coordinated triplet nitrene, (pi*)(4)(delta*)(1)(pi(nitrene,1))(1)(pi(nitren

155 s novel route involves the use of azide as a nitrene precursor, electronically-controlled regioselect

156 Azidoformates are interesting potential nitrene precursors, but their direct photochemical activ

157 to involve the formation of an intermediate nitrene prior to alkyl or aryl migration show no evidenc

158 ding evidence of the reactivity of the azido/nitrene probe substituent and close proximity to both re

159 The four photoactivated nitrene probes modified AChBP with up to one agonist for

160 osamine (R(2)NN=O) and an oxygen-substituted nitrene (R'ON).

161 e GES of 2N as Rh2(II,II) with a coordinated nitrene radical cation, (pi*)(4)(delta*)(2)(pi(nitrene,1

162 Thus, the formation of the second nitrene radical involves another intramolecular one-elec

163 The terminal copper(II)-nitrene radical species is able to transfer a nitrene mo

164 ic characterization of a terminal copper(II)-nitrene radical species that is stable at room temperatu

165 To fully characterize the Co(III)-'nitrene radical' species that are proposed as intermedia

166 e best described as [Co(III)(por)(NR''(*-))] nitrene radicals (imidyl radicals) resulting from single

167 hree ligand-centered unpaired electrons: two nitrene radicals (NR''(*-)) and one oxidized porphyrin r

168 ontrol to carbonyl O-oxides, whereas triplet nitrenes react much slower.

169 l azides are efficient sources for the metal nitrene reactive intermediate.

170 s above 40 K, and at these temperatures, the nitrene reacts with O2 to produce nitroso O-oxide mainly

171 elective oxyamination reaction with the same nitrene reagent generated in stoichiometric amounts.

172 lsion chemistry, and the isolation of formal nitrene rearrangement products of "1-AdN", "2-AdN" and "

173 source of nitrene fragments and interesting nitrene rearrangement products.

174 -((13)C-carbene) 22, which undergoes carbene-nitrene rearrangement to 2-naphthylnitrene 23.

175 In aqueous solutions singlet nitrenes relax (1.1 ps and 43 ns, respectively) to the l

176 At 77 K, the singlet nitrenes relax to the corresponding triplet nitrenes.

177 3)C label distribution requires that the non-nitrene route b contributes significantly.

178 te that an active, but still elusive, copper-nitrene (S = 1) intermediate initially abstracts a hydro

179 ent; in the presence of a 200-fold excess of nitrene scavenger, photoprobe 1 inactivates 92% of the K

180 t and diphenylphosphoryl azide (DPPA) as the nitrene source has been developed.

181 on with diphenylphosphoryl azide (DPPA) as a nitrene source.

182 Conversion of mono-nitrene species 3(P1)(Ns) into bis-nitrene species 5(P1)

183 (Troc) (TrocN3) led to the formation of mono-nitrene species 3(P1)(Ns), 3(P2)(Ts), and 3(P2)(Troc), r

184 s) results again in formation of mainly mono-nitrene species 3(P2)(Ns) according to EPR and ESI-MS sp

185 n of mono-nitrene species 3(P1)(Ns) into bis-nitrene species 5(P1)(Ns) upon reaction with 4(Ns) was d

186 lineNNs) 4(Ns) led to the formation of a bis-nitrene species 5(P1)(Ns).

187 ruling out the possibility of a common metal nitrene species and instead suggesting a rhodium-nitreno

188 XANES data revealed that both mono- and bis-nitrene species are six-coordinate O(h) species.

189 High-valent terminal copper-nitrene species have been postulated as key intermediate

190 Interestingly, this bis-nitrene species is observed only on reacting 4(Ns) with

191 n is mediated by a catalytic dirhodium-bound nitrene species that first behaves as a Lewis acid.

192 eaction starts with the formation of a metal-nitrene species that holds some radical character, and t

193 The mono- and bis-nitrene species were initially expected to be five- and

194 Upon generation at 10 K, the triplet nitrene spontaneously rearranges in the dark to singlet

195 on proceeds at rt without external oxidants, nitrene stabilizing groups, or directing functionality.

196 transfer to generate an open-shell singlet "nitrene-substrate radical, ligand radical", enabling sub

197 denosine diazaquinodimethane, the product of nitrene tautomerization, has a lifetime of ca. 1 min or

198 do not undergo ring expansion but form basic nitrenes that protonate to form nitrenium ions.

199 ther securing intramolecular addition of the nitrene, the intermolecular C-H amination remains much l

200 f abundant oxime, via rearrangement of the O-nitrene to a C-nitroso compound (R'ON --> O=NR'), and su

201 he photoinduced Curtius rearrangement of the nitrene to FNSO(2) was observed in solid noble gas matri

202 do decay by dimerizing with another triplet nitrene to form azo products, rather than reacting with

203 e intramolecular [1,4] H atom shift from the nitrene to the imino ketene occurs by tunneling, on the

204 ally abstracts a hydrogen atom from, or adds nitrene to, C-H and C horizontal lineC bonds, respective

205 indicate that [Mn((t)BuPc)] transfers bound nitrenes to C(sp(3))-H bonds via a pathway that lies bet

206 Nitrene transfer (NT) reactions represent powerful and d

207 Nitrene transfer from core imides is negligible.

208 capitalizing on an efficient stereoselective nitrene transfer involving the combination of a chiral a

209 e development of new catalysts for selective nitrene transfer is a continuing area of interest.

210 This species undergoes clean nitrene transfer on treatment with tert-butyl- or di-iso

211 n nitrogenated ligands can be used to tune a nitrene transfer reaction between two different types of

212 ext] We report here the first gold-catalyzed nitrene transfer reaction.

213 pecies that are proposed as intermediates in nitrene transfer reactions mediated by cobalt(II) porphy

214 stent with their proposed key involvement in nitrene transfer reactions mediated by cobalt(II) porphy

215 ilver-catalyzed, nondirected, intermolecular nitrene transfer reactions that are both chemoselective

216 lvability of the catalyst toward challenging nitrene transfer reactions.

217 reactions, as evidenced by the reaction with nitrene transfer reagents to form tantalum imido species

218 ns of cobalt(II) complexes of porphyrins and nitrene transfer reagents were combined, and the generat

219 of these bis(imido) complexes also promotes nitrene transfer to catalytically generate asymmetric di

220 Fe(kappa(2)-N4Ad2), undergoes intermolecular nitrene transfer to phosphine, abstracts H atoms from we

221 sfer, and transition-metal-catalyzed carbene/nitrene transfer, for the directed functionalization of

222 r histidine unlocks non-natural carbene- and nitrene-transfer activities.

223 trongly basic guanidinato moieties, mediates nitrene-transfer from PhI horizontal lineNR sources to a

224 Asymmetric nitrene-transfer reactions are a powerful tool for the p

225 pomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated an

226 As a result, the unreactive triplet state nitrene undergoes delayed, thermally activated reverse I

227 The singlet nitrene undergoes intersystem crossing (ISC) to the trip

228 r with chemoselectivity for insertion of the nitrene units into C-H bonds over reduction of the azide

229 product 11 indicates that 1 forms a singlet nitrene upon photolysis.

230 these complexes (lambda > 280 nm) results in nitrenes via the loss of nitrogen from the guest azidoad

231 Involvement of the O-nitrene was confirmed by trapping with 2,3-dimethyl-2-bu

232 g the reaction of phenylnitrene with O2, the nitrene was generated by flash vacuum thermolysis (FVT)

233 The intermediacy of the O-nitrene was inferred from the production of abundant oxi

234 vidence of products arising from the singlet nitrene was observed, indicating a slow rate of cyclizat

235 The triplet alkyl nitrenes were further characterized by obtaining their U

236 solution releases the corresponding singlet nitrene which rapidly tautomerizes to form a closed aden

237 ambient temperature again produces a singlet nitrene, which is too short-lived to detect by nanosecon

238 to reform the reactive closed-shell singlet nitrene, which subsequently protonates, forming the rema

239 talysts results in the formation of reactive nitrenes, which can undergo a variety of C-N bond-formin

240 It is unlikely that the nitrenes will undergo a Curtius-like rearrangement becau

241 rises from interception of the triplet alkyl nitrene with benzoyl radicals.

242 lid noble gas matrices, and reactions of the nitrene with O(2), NO, and CO were studied.

243 d by photoactivation of the azide group to a nitrene with single-pulse UV laser excitation.

244 modynamics and kinetics suggests that nickel-nitrenes with fluorinated phosphine supporting ligation

245 ion about exchange interactions in high-spin nitrenes with the pyrimidine ring and the mechanism of t

246 The behavior of nitrenes within OA differs from that in solution.

247 Reactivity of nitrenes within OA is different from that of carbenes th

248 yield LNi = NX + Y (L = bis-phosphine, NX = nitrene, Y = N2 or IPh).