Study of carbonyl oxide formation in the reaction of singlet oxygen with diphenyldiazomethane

Casal, H. L.; Sugamori, S. E.; Scaiano, J. C.

doi:10.1021/ja00336a053

Cited by 68 publications

(26 citation statements)

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“…In addition, the solution after the LFP was found to contain the corresponding benzophenone 1a -O as a major product. It is well documented that the oxygen trapping of diphenylcarbenes generates the corresponding benzophenone oxides with a broad absorption band at around 390–450 nm to afford the ketone derivative (Scheme 4) [40,41,42,43,44,45,46,47]. Thus, our observations suggested that carbene 3 1a was rapidly trapped with oxygen to form the ketone oxide 1a -O 2 like most of diphenylcarbenes.…”

Section: Resultssupporting

confidence: 51%

Diphenylcarbene Protected by Four ortho-Iodine Groups: An Unusually Persistent Triplet Carbene

et al. 2016

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Diphenyldiazomethane with four iodine groups at the ortho positions and two tert-butyl groups at the para positions, i.e., bis(4-tert-butyl-2,6-diiodophenyl)diazomethane (1a-N 2 ), was synthesized as a sterically hindered triplet carbene precursor. Irradiation of 1a-N 2 in solution effectively generated the corresponding triplet diphenylcarbene 3 1a, which was characterized by UV-vis spectroscopy at low temperature, along with laser flash photolysis techniques at room temperature. The UV-vis spectrum of 3 1a was obtained by irradiating 1a-N 2 in a 2-methyltetrahydrofuran matrix at 77 K. The ESR spectrum showed no triplet carbene signals, while a radical species was observed at the anticipated temperature of the decomposition of triplet carbene 3 1a. Transient absorption bands ascribable to 3 1a were observed by laser flash photolysis of 1a-N 2 in a degassed benzene solution and decayed very slowly with a second-order rate constant (2k/εl) of 5.5 × 10 −3 ·s −1 . Steady-state irradiation of 1a-N 2 in degassed benzene afforded 9,10-diarylphenanthrene derivative 2a in a 31% yield. Triplet carbene 3 1a was also trapped by either oxygen (k O2 = 6.5 × 10 5 M −1 ·s −1 ) or 1,4-cyclohexadiene (k CHD = 1.5 M −1 ·s −1 ) to afford the corresponding ketone 1a-O or the diarylmethane 1a-H 2 . The carbene was shown to be much less reactive than the triplet diphenylcarbene that is protected by two ortho-iodo and two ortho-bromo groups, 3 1b.

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Section: Resultssupporting

confidence: 51%

Diphenylcarbene Protected by Four ortho-Iodine Groups: An Unusually Persistent Triplet Carbene

et al. 2016

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“…The spent solution was found to contain the corresponding benzophenone. It is well‐documented48–55 that diarylcarbenes with triplet ground states are readily trapped by oxygen to generate the corresponding diaryl ketone oxides (Scheme ), which show a broad absorption band centered at 390–450 nm. Thus, our observations can be interpreted as indicating that the transient absorption quenched by oxygen is due to 3 1a .…”

Section: Resultsmentioning

confidence: 99%

Triplet diphenylcarbene protected by iodine and bromine groups

Hirai

Bessho

Kitagawa

et al. 2010

J of Physical Organic Chem

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Diphenyldiazomethane having two iodine and two bromine groups at the ortho positions, (2,6‐dibromo‐4‐tert‐butylphenyl)(2,6‐diiodo‐4‐tert‐butylphenyl)diazomethane (1a‐N2), has been synthesized. Triplet diphenylcarbene 31a is generated from the precursor and is characterized by UV–Vis spectroscopy at low temperature and laser flash photolysis (LFP) techniques at room temperature. Irradiation of 1a‐N2 in a 2‐methyltetrahydrofuran (2‐MTHF) matrix at 77 K gives the UV–Vis spectrum of 31a, but ESR signals that can be assigned to a triplet species are not detected. The LFP of 1a‐N2 in a degassed benzene solution produces the transient absorption ascribable to 31a at 351 nm, which decays in a second‐order process with a rate constant of 0.17 s−1. The first half‐life of 31a is estimated to be 24 s. Triplet carbene 31a is trapped by oxygen to generate benzophenone oxide 1a‐O, with maximum absorbance at 415 nm, with a rate constant of 7.3 × 106 M−1s−1, and also by 1,4‐cyclohexadiene (CHD) to produce the diphenylmethyl radical (1a‐H2, λmax = 380 nm) with a rate constant of 39 M−1s−1. The carbene is also trapped by methanol with a rate constant of 0.30 M−2s−1. Steady‐state irradiation of 1a‐N2 in degassed benzene affords only a small amount of the phenanthrene 2a as an assignable product. Copyright © 2010 John Wiley & Sons, Ltd.

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“…The spent solution was found to contain the corresponding benzophenone. It is well‐documented that diarylcarbenes with triplet ground states are readily trapped by oxygen to generate the corresponding diaryl ketone oxides, which show a broad absorption band from 360 to 480 nm (Scheme ). Thus, our observations can be interpreted as indicating that the transient absorption quenched by oxygen is due to 3 1b .…”

Section: Resultsmentioning

confidence: 99%

Generation and reactivities of triplet diphenylcarbenes protected by bulky groups as para substituents

Hirai

Hatanaka

Yamaguchi

et al. 2011

J of Physical Organic Chem

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Bis(2,6‐dimethylphenyl)diazomethane (1b‐N2) having 10‐(4‐tert‐butyl‐2,6‐dimethylphenyl)‐2,7‐di(phenylethynyl)‐9‐anthrylethynyl groups at the 4,4′‐positions was synthesized. Triplet diphenylcarbene 31b was generated by photolysis of the precursor and was characterized by electron spin resonance and UV–Vis spectroscopies at low temperature, and laser flash photolysis techniques at room temperature. Irradiation of 1b‐N2 in a 2‐methyltetrahydrofuran matrix at 77 K gave electron spin resonance signals ascribable to triplet carbene 31b. UV–Vis spectra of 31b were obtained by irradiating 1b‐N2 under identical conditions. The laser flash photolysis of 1b‐N2 in a degassed benzene solution gave transient absorption bands ascribable to 31b, which decayed in a first‐order fashion with a rate constant of 0.46 s–1. The carbene was shown to be less reactive than the triplet bis(2,6‐dimethylphenyl)carbene (31a) having 9‐anthrylethynyl groups at the 4,4′‐positions, which decayed in a second‐order fashion with a rate constant (2 k/εl) of 0.69 s–1. Triplet carbene 31b was trapped by oxygen to generate ketone oxide 1b‐O with a rate constant of 1.9 × 107 M–1 s–1 and also by 1,4‐cyclohexadiene with a rate constant of 1.2 M–1 s–1. Similar studies with diphenyldiazomethanes (1c‐N2 and 1 d‐N2) having bulky substituents, 10‐(4‐tert‐butyl‐2,6‐dimethylphenyl)‐2,7‐bis[3,5‐di(phenylethynyl)phenylethynyl]‐9‐anthrylethynyl and 10‐(4‐tert‐butyl‐2,6‐dimethylphenyl)‐2,7‐bis(9‐triptycylethynyl)‐9‐anthrylethynyl groups at the 4,4′‐positions respectively indicated that the corresponding triplet carbenes 31c and 31 d were more persistent than 31b. Steady‐state irradiation of 1a‐N2, 1c‐N2, and 1 d‐N2 in degassed benzene afforded tetraarylethenes 2a, 2c, and 2d in 83, 50, and 51% yield, respectively. Copyright © 2011 John Wiley & Sons, Ltd.

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Study of carbonyl oxide formation in the reaction of singlet oxygen with diphenyldiazomethane

Cited by 68 publications

References 0 publications

Diphenylcarbene Protected by Four ortho-Iodine Groups: An Unusually Persistent Triplet Carbene

Diphenylcarbene Protected by Four ortho-Iodine Groups: An Unusually Persistent Triplet Carbene

Triplet diphenylcarbene protected by iodine and bromine groups

Generation and reactivities of triplet diphenylcarbenes protected by bulky groups as para substituents

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