�ber Carbons�ureester der Phloroglucine

Herzig, J.; Wenzel, F.

doi:10.1007/bf01526666

Cited by 9 publications

(11 citation statements)

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“…The alternative method, which involved DCC coupling of an oxime with the corresponding carboxylic acid (catalysed by DMAP), was usually more convenient and often led directly to crystalline products without the need to resort to column chromatography (Method B). The oximes (1) chosen for investigation, which were prepared using standard methods from the corresponding aldehyde and hydroxylamine hydrochloride, were benzaldoxime, 9 4-nitrobenzaldoxime, 9 pentafluorobenzaldoxime, 10 2,4-dimethoxybenzaldoxime, 11 2,4,6trimethoxybenzaldoxime, 12 and benzophenone oxime. 9 Oxime esters 3-7a, b, e-g, i-l and 8 were prepared mainly for EPR investigations and to examine intermolecular addition, whilst 3-7c, d, and h were prepared primarily for examination of intramolecular reactions.…”

Section: Preparation Of Oxime Estersmentioning

confidence: 99%

Exploitation of aldoxime esters as radical precursors in preparative and EPR spectroscopic roles

McCarroll

Walton

2000

J. Chem. Soc., Perkin Trans. 2

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Photolyses of aldoxime esters, containing a considerable range of alkyl groups, lead to cleavage of their N-O bonds and formation of aryliminyl and alkyl radicals. The process was found to be favoured by 4-methoxyacetophenone as a photosensitiser and by methoxy substituents in the aryl rings. 4-Nitro-and pentafluoro-substitutions of the aryl rings were, on the other hand, deleterious. The intermediate iminyl radicals, together with primary, secondary and tertiary alkyl radicals were characterised by 9 GHz EPR spectroscopy. Cyclopropyl, CF 3 , and CCl 3 radicals were probably also formed, but were too reactive for direct EPR spectroscopic detection. Photosensitised reaction of benzophenone oxime O-nonanoyl ester produced the diphenylmethaniminoxyl, as well as the expected n-octyl and iminyl radicals. This indicated that O-C bond scission accompanied O-N scission for this ketoxime ester.At higher temperatures the C-centred radicals added to the starting oxime esters to produce alkoxyaminyl radicals that were also spectroscopically detected in some cases. No evidence for abstraction of the iminyl hydrogen by tertbutoxyl radicals was obtained. Instead, the t-BuO ؒ radicals added to the C᎐ ᎐ N double bonds of the oxime esters. Similarly, chlorine abstraction from alkylbenzohydroximoyl chlorides by trimethyltin radicals did not take place. Preparative scale experiments with oxime esters containing suitably unsaturated alkyl groups showed that good yields of cyclised products could be obtained in the presence of the photosensitiser. This process constitutes a general method by which carboxylic acids or acid chlorides can be converted into alkyl radicals and hence to cyclised derivatives.

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Section: Preparation Of Oxime Estersmentioning

confidence: 99%

Exploitation of aldoxime esters as radical precursors in preparative and EPR spectroscopic roles

McCarroll

Walton

2000

J. Chem. Soc., Perkin Trans. 2

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show abstract

“…syn-Benzaldoxime, 14 p-nitrobenzaldoxime, 14 pentafluorobenzaldoxime, 27 2,4-dimethoxybenzaldoxime, 28 2,4,6-trimethoxybenzaldoxime, 29 N-tert-butoxyphthalimide, 13 N-isopropoxyphthalimide, 30 potassium benzohydroximate, 21 O-isopropyl benzohydroxamate, 22 O-n-propyl benzohydroxamate, 23 O-isopropyl benzohydroximoyl chloride, 22 O-n-propyl benzohydroximoyl chloride 23 and di-tert-butyl peroxyoxalate 31 were prepared as described in the literature.…”

Section: Discussionmentioning

confidence: 99%

“…401, dodecanol, 168 (M ϩ Ϫ H 2 O) (1), 140 (4), 97 (11), 83 (26), 69 (36), 56 (48), 55 (90), 43 (79), 41 (100), 29 (62); peak no. 401, 2,4,6-trimethoxybenzonitrile, 193 (M ϩ ) (100), 164 (35), 150 (28), 104 (29), 77 (40), 76 (31), 69 (80), 55 (43), 41 (48), 29 (34); peak no. 556, unreacted 7d.…”

Section: Photochemical Reactions Of Oxime Ethers In Di-tert-butyl Per...mentioning

confidence: 99%