Nitrones phosphorylated

Determination of electrochemical oxidation potentials and electrochemical reduction of 13 p-phosphorylated acyclic nitrones shows that phosphorylated compounds have a clear anodic shift of potentials of both, oxidation (Ep 1.40 to 2.00 V versus SCE in CH3CN) and reduction (Ep—0.94 to —2.06 V). This is caused by a strong electron-acceptor influence of the diethoxyphosphoryl group (430). In contrast, a reversible one-electron oxidation of azulene nitrones (233) (Scheme 2.80) occurs 0.6 V below the Ep potential of PBN, that is at the value one observes the oxidation of AH -imidazole-1,3-dioxides (219) (428, 429). In other words, the corresponding RC (234) is 14 kcal more stable than the RC of PBN. Although the EPR spectrum of RC (234) was not recorded, RC (236) from dinitrone (235) turned out to be rather stable and gave an EPR spectrum (170). 

Nitrone reactions with lithiated dialkyl phosphite results in the formation of a-(hydroxyamino)phosphonate, which, depending on the character of the R substituent at a-C lead to a-phosphorylated nitrones (429) or fS-phosphorylated nitroxyl radicals (430) after successive oxidations (Scheme 2.200) (686—689). 

Cycloaddition of N-substituted C -phosphorylated nitrones (496) to terminal alkenes leads to C-5 substituted isoxazolidines (497) and (498) with moderate (20%) to high (up to 90%) trans to cis diastereoselectivities (Scheme 2.241) (Table 2.20). In ZnCl2-catalyzed cycloadditions, mixtures enriched in cis diastere-omers were produced (263). 

To carry out 1,3-dipolar cycloadditions with alkyl acrylates, nitrones of various structures such as ferrocenylnitrones (141), nitrones derived from chiral amino acids (210), L-serine-derived nitrones (660) and N -substituted C -phosphorylated nitrones (263) have been used. 

Zeghdaoui A, Finet JP, Tuccio B, Cerri V, Tordo P. Derives phosphoryles de nitrones, leur precede de preparation et compositions les contenant, French Patent No. 9502598, 06 March 1995. 

In addition to (aminoalkyl)phosphonic diesters, several other, well characterized products have been obtained from the oximes, or derivatives of oximes, of acylphosphonic diesters. Methylation of the oximes 283 [Z = CONHR, COOR (R = Et or Pr ), R = H of undefined geometry] with MeI-K2C03, or with Me2S04, yields the O-methyl oximes 283 (Z = CONHR R = Me) methylation with diazomethane also yields the latter but together with the phosphorylated nitrones 284 (Z = CONHR or COOR), which have been characterized in E and Z forms. The interaction of283 (R = Me) and diazomethane yields the corresponding 285 . Methylene insertion also occurs in reactions between diazomethane and 0-acylated oximes ... 

The amination of allenylphosphonates (191), including those with nucleobases, takes place readily even in the absence of a transition metal catalyst leading to a single isomer of (enamino)vinyl or (enamino)allyl phosphonate while traditional allenes under these conditions remained unreactive towards nitrogen nucleophiles.Phosphorylated nitrones (192) have been synthesized by Swem oxidation of hydroxymethylphosphonates. Cycloaddition of nitrone (192) with 1-alkenes led to almost exclusively to the formation of C5-substituted isoxazolidines (193) (Scheme 68). ... 

Another phosphorylated spin trap, 5-diethoxyphosphoryl-5-methyl-l-pyrroline-(V-oxide [DEPMPO (16)], has been employed to distinguish radical reactions that produce HO from those that proceed via one-electron transfer followed by hydration or nucleophilic substitution, to give apparent radical adducts. The same spin trap was one of several nitrones employed to study the decomposition of three water-soluble amidino-azo initiators (proposed as potential sources of alkylperoxy and alkoxyl radicals). ... 

Benzoxazoies.—Benzoxazoles (559) are obtained by the action of the thio-phosphoryl compound PhPS(OMe)2 on the nitrones (558). The naphthaquinones (560 R = H, Me, Ph, or NH2) cyclise to the naphtho[2,3-condensed oxazole (562) on treatment with ethyl azidoformate. Acenaph-tho[l,2-d]oxazoles (564 R = Me, Et, or Ph) are formed when 2-diazoacenaph-thenone (563) is irradiated in the presence of cyanides RCN. Phenanthro-oxazoles result when 2-aryl-4,5-diphenyl-oxazoles are irradiated in the presence of oxygen or iodine the p-nitrophenyl derivative is obtained by the action of p-nitrobenzyl chloride on the monoimine or the mono-oxime of phenan-thraquinone, ... 

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