Methoxyphenyldiazirine as precursor to methoxyphenylcarbene

Wlostowska, J.; Moss, Robert A.; Guo, Wenjeng; Chang, Ming Jing

doi:10.1039/c39820000432

Cited by 26 publications

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“…(c) Methoxyphenylcarbene. 3-Methoxy-3-phenyldiazirine ( 1c ) was prepared by the exchange reaction of 3-bromo-3-phenyldiazirine with sodium methoxide in dimethylformamide (DMF) as described previously. 9b, Diazirine 1c has a lifetime of 4−5 min at room temperature and does not survive for long periods even when stored on dry ice. Therefore, this precursor was prepared just prior to use.…”

Section: Resultsmentioning

confidence: 99%

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Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes¹

et al. 1998

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Laser flash photolysis (UV-LFP) studies of benzylchlorodiazirine (1a), phenylchlorodiazirine (1b), phenylmethoxydiazirine (1c), 2,2-dimethoxy-5,5-dimethyl-∆ 3 -1,3,4-oxadiazoline (6a), 3,4-diaza-2,2-dimethoxy-1-oxa[4.3]spirooct-3-ene (6b), 5′,5′-dimethoxyspiro[adamantane]-2,2′-[∆ 3 -1,3,4-oxadiazoline] (6c), and diazofluorene (DAF) in the presence of oxiranes and thiiranes are reported. These compounds, upon irradiation, afford benzylchlorocarbene (2a), phenylchlorocarbene (2b), methoxyphenylcarbene (2c), dimethylcarbene (8a), cyclobutylidene (8b), adamantylidene (8c), and fluorenylidene (FL), respectively. Absolute rate constants for the transfer of oxygen and sulfur atoms to these carbenes have been determined in both acetonitrile and cyclohexane solvents. These carbenes abstract oxygen and sulfur atoms with bimolecular rate constants ranging from 10 4 to 10 10 M -1 s -1 at 22°C. Ylides from attack of carbenes onto heteroatom donors were not observed for any of the heteroatom transfer reactions. It was found that the magnitudes of the rate constants for heteroatom transfer are dependent on the philicity of the carbene intermediate, and trends in the kinetic data suggest that oxygen and sulfur atom transfers occur by concerted mechanisms through ylide-like transition states. The reactions of dimethoxycarbene (14) with cyclohexene oxide and propylene sulfide have been studied by the thermolysis of 6a, in benzene, at 110°C. It was found that dimethoxycarbene also abstracts oxygen and sulfur atoms, albeit in low yields. It is concluded that, for singlet carbenes, carbene electrophilicity is important in these heteroatom transfer processes.S0002-7863(97)03469-0 CCC: $15.00

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Section: Resultsmentioning

confidence: 99%

“…UV − Vis. The nanosecond laser system has been described previously . Sample solutions were prepared with absorbances (A) of 0.3−0.6 at the excitation wavelength (355 or 308 nm) as described below.…”

Section: Methodsmentioning

confidence: 99%

Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes¹

et al. 1998

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“…40 Similarly, reaction of 5 (R = Ph, X = Br) with NaOMe gave phenylmethoxydiazirine 6 (R = Ph, Y = OMe). 41 With hard nucleophiles, such as fluoride or methoxide, the mechanism of these diazarine-exhange reactions appears to involve successive S N 2′ attacks on 5, initially affording an intermediate isodiazirine 7 and subsequently diazirine 6. 42 With softer nucleophiles, such as acetate or azide, diazirine exchange involves radical intermediates.…”

Section: Diazirine-exchange Reaction and Derived Carbenesmentioning

confidence: 99%

“…Thus, reaction of 5 (e.g., R = aryl, X = Br) with tetrabutylammonium (TBA) fluoride afforded fluorodiazirine 6 (Y = F) . Similarly, reaction of 5 (R = Ph, X = Br) with NaOMe gave phenylmethoxydiazirine 6 (R = Ph, Y = OMe) . With hard nucleophiles, such as fluoride or methoxide, the mechanism of these diazarine-exhange reactions appears to involve successive S N 2′ attacks on 5 , initially affording an intermediate isodiazirine 7 and subsequently diazirine 6 .…”

Section: Diazirine-exchange Reaction and Derived Carbenesmentioning

confidence: 99%

Adventures in Reactive Intermediate Chemistry: A Perspective and Retrospective

Moss

2017

J. Org. Chem.

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I review aspects of my research on reactive intermediates, specifically the physical organic chemistry of carbenes and carbocations. The topics treated include carbenoids, carbenic philicity, absolute rates of carbene/alkene additions, the diazirine exchange reaction and derived carbenes, carbene equilibria, carbocations from diazotates, and carbocations from alkoxychlorocarbenes. The essay concludes with observations on the protean nature of physical organic chemistry.

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“…Y = OR, OAr, F, OAc, CN, N 3 , or NR 2 . The first example (1982) was the conversion of phenylbromodiazirine ( 8 , R = Ph, X = Br) to phenylmethoxydiazirine ( 9 , R = Ph, Y = OMe) 19. Since then many analogous reactions have been reported; a table in our 2006 review includes 34 examples 9…”

Section: Graham's Reaction and The Diazirine Exchange Reactionmentioning

confidence: 99%

Dihalodiazirines and the photochemical generation of dihalocarbenes: new light on old problems

Moss

2009

J of Physical Organic Chem

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The Graham oxidation of amidines to halodiazirines, coupled with the diazirine exchange reaction, makes available many new diazirine precursors of carbenes. Nitration of the phenoxy moieties of phenoxychloro‐ or phenoxyfluorodiazirine converts them to leaving groups, ultimately permitting the preparations of CCl2, CClF, and CF2. Absolute rate constants and activation parameters are measured for the additions of these carbenes to several alkenes. The comparative contributions of ΔH‡ and ΔS‡ to ΔG‡ are assessed for these reactions, as are the dependences of ΔH‡ and ΔS‡ on the structures and reactivities of the carbenes and alkenes. Copyright © 2009 John Wiley & Sons, Ltd.

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Methoxyphenyldiazirine as precursor to methoxyphenylcarbene

Cited by 26 publications

References 1 publication

Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes¹

Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes¹

Adventures in Reactive Intermediate Chemistry: A Perspective and Retrospective

Dihalodiazirines and the photochemical generation of dihalocarbenes: new light on old problems

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Methoxyphenyldiazirine as precursor to methoxyphenylcarbene

Cited by 26 publications

References 1 publication

Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes1

Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes1

Adventures in Reactive Intermediate Chemistry: A Perspective and Retrospective

Dihalodiazirines and the photochemical generation of dihalocarbenes: new light on old problems

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Product

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About

Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes¹

Laser Flash Photolysis Studies of Oxygen and Sulfur Atom Transfer Reactions from Oxiranes and Thiiranes to Singlet Carbenes¹