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Aziridines iodo azides

P-Iodo azides can be reduced to aziridines with LiAlH4 or converted to N-alkyl- or N-arylaziridines by treatment with an alkyl- or aryidichloroborane fol-... [Pg.1046]

Neither aromatic halogens [232,602] nor nitro groups were affected during the reductions of the azido group [232, 247, 602]. a-Iodo azides gave, on reduction, aziridines or alkenes depending on the substituents and on the reagents used [603]. [Pg.76]

The iodo azide undergoes stereospecific trans dehydrohalogenation to give a vinyl azide, which on photolysis or pyrolysis gives the 2H-azirine. Reduction of the 2H-azirine with lithium aluminium hydride gives the m-aziridine in good yield. [Pg.388]

Aziridino-steroids (e.g. 486) are available by reduction of suitable iodo-azides with lithium aluminium hydride, but fewer side-reactions occur if the iodo-azide (484) is first treated with triphenylphosphine, or with a phosphite ester. Loss of nitrogen leads to the iV-phosphonium aziridine derivative (485), which is smoothly reduced by lithium aluminium hydride to give the aziridine. The exact mechanism of nitrogen loss in the first step is uncertain. [Pg.352]

Iodine azide, on the other hand, forms pure adducts with A -, A - and A -steroids by a mechanism analogous to that proposed for iodine isocyanate additions. Reduction of such adducts can lead to aziridines. However, most reducing agents effect elimination of the elements of iodine azide from the /mwj -diaxial adducts of the A - and A -olefins rather than reduction of the azide function to the iodo amine. Thus, this sequence appears to be of little value for the synthesis of A-, B- or C-ring aziridines. It is worthy to note that based on experience with nonsteroidal systems the application of electrophilic reducing agents such as diborane or lithium aluminum hydride-aluminum chloride may yet prove effective for the desired reduction. Lithium aluminum hydride accomplishes aziridine formation from the A -adducts, Le., 16 -azido-17a-iodoandrostanes (97) in a one-step reaction. The scope of this addition has been considerably enhanced by the recent... [Pg.24]

The dipolar cycloaddition of an alkyl azide with an alkene to form an aziridine has been exploited in the total synthesis of the alkaloid ( )-aspidospermidine <20050BC213>. Enone 353 was prepared in 11 steps from 3-ethoxycyclohexenone and coupled to 2-iodo nitrobenzene under Ullman cross-coupling conditions. The acetate group of 354 was hydrolyzed and the resulting alcohol converted to an azide using standard conditions in 75% overall yield. The cycloaddition of the azide with the enone was conducted in refluxing benzene for 3 days. The fused-ring aziridine 355 was the only product isolated. None of the initial dipolar cycloadduct triazoline was observed. The... [Pg.164]

A variety of alkenes undergo azidoiodination with sodium azide, potassium iodide, and Oxone on wet alumina to give azido-iodo compounds regioselectively in high yield (eq 79). These compounds are useful precursors to vinyl azides, amines, and aziridines and are typically synthesized with more expensive and exotic reagents. Similar methods have been used in the iodolac-tonization and iodoetherification of unsaturated carboxylic acids and alcohols to make five- and six-membered lactones, tetrahy-drofurans, and tetrahydropyrans (eq 80). ... [Pg.343]

A novel method of synthesis of /8-glycosides (including disaccharides) of 2-acetamido-2-deoxy-D-glucose uses 2-deoxy-2-iodo-D-mannosyl azide (prepared from tri-O-acetyl-D-glucal) which gives access to the glycosides (via aziridine intermediates) on treatment with triphenylphosphine and alcohols in dichloromethane. In similar fashion, the D-gluco-iodoazide affords the 2-acetamido-2 -deoxy-a-D-mannopyranosides. [Pg.19]


See other pages where Aziridines iodo azides is mentioned: [Pg.401]    [Pg.697]    [Pg.704]    [Pg.85]    [Pg.28]    [Pg.322]    [Pg.85]    [Pg.123]    [Pg.85]    [Pg.22]    [Pg.526]    [Pg.49]    [Pg.27]    [Pg.72]    [Pg.85]    [Pg.388]   
See also in sourсe #XX -- [ Pg.76 , Pg.183 ]




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Iodo azides

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