Photoreduction of benzaldehyde N-alkylimines

Padwa, Albert; Bergmark, William R.; Pashayan, Deran

doi:10.1021/ja01018a048

Cited by 30 publications

(11 citation statements)

References 2 publications

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“…The interest in n-rr* states stems from the fact that in carbonyl group photochemistry they have been designated as the reactive state in hydrogen abstraction and other types of reaction 42 • Extending this reasoning, some workers 43 • 44 have suggested that the n-rr* excited state of the imine is the reactive state in photoreduction. Our studies 24 on the photoreduction of benzaldehyde N-alkylimines disclosed a number of disquieting features which altered this conception of the reaction.…”

Section: Introductionmentioning

confidence: 94%

Recent advances in the photochemistry of the carbon-nitrogen double bond

Padwa¹,

Dharan²,

Smolanoff³

et al. 1973

Pure and Applied Chemistry

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The excited states of imines were shown nottobe reactive intermediates in the photoreduction of a series of benzaldehyde N-alkylimines. Instead, ketyl radicals were clearly implicated as the active reducing agent. These ketyl radicals were derived from carbonyl compounds present in the reaction mixture as an impurity, an added sensitizer, or as a photogenerated species. The Iack of reactivity of the excited state of simple imines suggests that the excited states undergo a very efficient non-radiative decay to ground state thereby precluding hydrogen abstraction. This facile energy deactivation is a consequence of rotation about the C-N double bond (i.e. syn-anti photoisomerization). In rigid systems, this mode of energy dissipation would not be available and these molecules would have maximum opportunity to undergo reaction from an electronically excited state.ln this regard, the photocycloaddition of arylazirenes with electron deficient olefins to give !l.' -pyrrolines has been examined in mechanistic detail. The formation of the adduct was interpreted as proceeding by way of irreversible opening of the azirene ring to form a nitrile ylide intermediate which is then trapped by a suitable dipolarophile. Irradiation of a number of substituted arylazirenes in an inert solvent gives 1,3-diazabicyclo-[3.l.O]hex-3-enes as primary photoproducts. The formation of these dimers can be rationalized by 1 ,3-dipolar addition of the initially generated nitrile ylide on to a ground state azirene molecule. Support for this conclusion was obtained by a study of the variation of the quantum yield for adduct formation as a function of the concentration of added dipolarophile. The study shows that the amount of adduct formed is dependent on the initial concentration of arylazirene and on the activity of the dipolarophile.

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Section: Introductionmentioning

confidence: 94%

Recent advances in the photochemistry of the carbon-nitrogen double bond

Padwa¹,

Dharan²,

Smolanoff³

et al. 1973

Pure and Applied Chemistry

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“…Finally, the absence of significant difference between the mass spectra of compound I before and after irradiation excludes the possibility of hydrolysis or dimerization-the processes most frequently encountered in irradiated azomethines (see, e.g., [22][23][24]). …”

Section: Resultsmentioning

confidence: 99%

Laser-induced photoconversion of nitrofuran preparations

et al. 1999

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“…(148)] is available from the reaction of 2-acylcyclohexanones with malononitrile or cyanoacetamide.' 64 Two new methods of side-chain functionalisation have been described. Thus, peracid oxidation of 2-benzyloxy-6-methylpyridine yields 1 -benzyloxy-6-methyl 2-pyridone, which, possessing an active methyl group, can undergo condensation with carbonyl derivatives.…”

Section: Nh2 H (136) C02etmentioning

confidence: 99%

Chapter 13. Heterocyclic chemistry

Stoodley¹

1968

Annu. Rep. Prog. Chem., Sect. B

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Three-membered Rings.-The existence of a high barrier to nitrogen inversion in aziridines, which contain a hetero-atom attached to the ring nitrogen, may be inferred from n.m.r. spectroscopy.l An elegant demonstration of this effect is provided by 1-chloro-2-methyla~iridine~ and 7-chloroazabicyclo[4,1,0] although the adducts generally undergo rearrangement. For example, 2,4diphenylpyrrole is formed from 2-phenyl-1-azirine and acetophenone in the presence of a strong base,g diazomethane and 3-methyl-2-phenyl-1-azirine react to give a mixture of cis-and transl-azido-2-phenyl-but-2-ene together with 3-azido-2-phenyl-but-1 -ene, l o while a-ammoniumisobutyrophenone anil perchlorate is obtained from 3,3-dimethyl-2-phenyl-l-azirine and anilinium perchlorate." Even acid chlorides and acid anhydrides will add to the azirine double-bond :' the N-acylchloroaziridines derived from benzoyl chloride and 3-methyl-2-phenyl-1-azirine are stable in benzene, although they readily rearrange to 4-methyl-2,5-diphenyloxazole and the dichloro-amide (4) in acetone . Ph,CH .CO* NPh. CH(0Me)Ph

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Photoreduction of benzaldehyde N-alkylimines

Cited by 30 publications

References 2 publications

Recent advances in the photochemistry of the carbon-nitrogen double bond

Recent advances in the photochemistry of the carbon-nitrogen double bond

Laser-induced photoconversion of nitrofuran preparations

Chapter 13. Heterocyclic chemistry

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