Triplet-sensitized photolysis of alkoxycarbonyl azides in solution and matrices

Murthy, Rajesh S.; Muthukrishnan, Sivaramakrishnan; Rajam, Sridhar; Mandel, Sarah M.; Ault, Bruce S.; Guđmundsdóttir, Anna D.

doi:10.1016/j.jphotochem.2008.10.015

Cited by 15 publications

(14 citation statements)

References 41 publications

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“…Whereas most alkoxycarbonyl and acyl nitrene derivatives and imidogen can be anticipated to undergo H‐atom abstractions, most alkyl, vinyl, and phenyl nitrene derivatives cannot. These results fit with what has been reported, because alkoxycarbonylnitrenes undergo efficient H‐atom abstraction in solution to form the corresponding amines 45, 46. Similarly, imidogen undergoes H‐atom abstraction in the gas phase; however, the reactivity of triplet imidogen has not been reported in solution to date.…”

Section: Resultssupporting

confidence: 90%

The ability of triplet nitrenes to abstract hydrogen atoms

Sankaranarayanan

Rajam

Hadad

et al. 2010

J of Physical Organic Chem

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The enthalpies for H‐atom abstraction reactions by triplet imidogen as well as ethyl, alkoxycarbonyl, acyl, phenyl, and vinyl nitrenes were calculated using density functional theory calculations. These calculations show that H‐atom abstraction reactions are only feasible for triplet imidogen, alkoxycarbonyl, and acyl nitrenes in solution. The calculated charges on the N‐atoms (QNPA) in the nitrene correlate with the magnitude of the transition state barrier for the H‐atom abstraction reactions from methanol as a model reactant. Electron‐withdrawing substituents on these nitrenes make them less stable but do not affect the transition state barrier significantly. Thus, as the electron deficiency of the N‐atom in the nitrenes is increased, the H‐atom abstraction reaction becomes more feasible. Copyright © 2010 John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 90%

The ability of triplet nitrenes to abstract hydrogen atoms

Sankaranarayanan

Rajam

Hadad

et al. 2010

J of Physical Organic Chem

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“… − Similar work in Germany also demonstrated that photochemical decomposition of t -butyloxycarbonylazide ( 3 ) produces t -butyloxycarbonylnitrene ( 4 ) that predominantly gives 5,5-dimethyl-2-oxazolidinone ( 5 ) via an intramolecular C–H insertion reaction in a variety of solvents (Scheme ). − More recent synthetic and spectroscopic studies on oxycarbonylnitrenes have confirmed the above reactivity and provided additional insight into these interesting reactive intermediates. − …”

Section: Introductionmentioning

confidence: 80%

Time-Resolved Infrared (TRIR) Studies of Oxycarbonylnitrenes

2016

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N-Ethyloxycarbonyl-S,S-dibenzothiphene sulfilimine and N-t-butyloxycarbonyl-S,S-dibenzothiphene sulfilimine have been utilized as precursors to ethoxycarbonylnitrene and t-butyloxycarbonylnitrene. B3LYP/6-31G(d) calculations predict triplet ground states for both oxycarbonylnitrenes, albeit by small margins. Triplet ethoxycarbonylnitrene and triplet t-butyloxycarbonylnitrene have been observed following photolysis of these sulfilimine precursors by time-resolved infrared (TRIR) spectroscopy. Kinetic studies show that ethoxycarbonylnitrene reacts with solvents such as acetonitrile and cyclohexane, while t-butyloxycarbonylnitrene undergoes an intramolecular insertion reaction to produce 5,5-dimethyl oxazolidinone. Product analysis following photolysis of N-t-butyloxycarbonyl-S,S-dibenzothiphene sulfilimine confirms that the oxazolidinone is the major product with an estimated yield of 90%. The products from these two nitrenes are derived from the corresponding singlet nitrene, either directly or via thermal repopulation of the singlet from the lower-energy triplet nitrene.

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“…Electron‐donating substituents stabilize triplet nitrene intermediates, whereas electron‐withdrawing substituents render them more reactive. For example, triplet carboalkoxynitrenes are short‐lived, as they abstract H atoms from the solvent . In comparison, triplet alkylnitrenes and arylnitrenes are less reactive and longer‐lived, as they do not react with the solvent, but mainly decay by dimerization (Scheme ) .…”

Section: Introductionmentioning

confidence: 99%

Photolysis of 3,5‐diphenylisoxazole in argon matrices

Sriyarathne

Sarkar

Hatano

et al. 2016

J of Physical Organic Chem

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Broadband irradiation of 3,5‐diphenylisoxazole 1 in an argon matrix results in formation of azirine 3. Further irradiation of the matrix reduces the amount of azirine 3 with concurrent formation of ylide 4. Thus, it is theorized that the conversion of isoxazole 1 to azirine 3 goes through a triplet vinylnitrene 2 that does not intersystem cross to ketenimine 6. Hence, the reactivity of triplet vinylnitrene 2 is different from similar vinylnitrene intermediates with α‐methyl substituents that intersystem cross to form corresponding ketenimines. Density functional theory calculations support the notion that the conjugation of the α‐phenyl group to the vinylnitrene moiety in vinylnitrene 2 renders it more flexible than vinylnitrenes with α‐methyl substituents, and therefore, vinylnitrene 2 intersystem crosses to azirine 3, rather than ketenimine 6. Copyright © 2016 John Wiley & Sons, Ltd.

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Triplet-sensitized photolysis of alkoxycarbonyl azides in solution and matrices

Cited by 15 publications

References 41 publications

The ability of triplet nitrenes to abstract hydrogen atoms

The ability of triplet nitrenes to abstract hydrogen atoms

Time-Resolved Infrared (TRIR) Studies of Oxycarbonylnitrenes

Photolysis of 3,5‐diphenylisoxazole in argon matrices

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