Azides phosphorus ylides

Ykman, P., L Abbe, G. and Smets, G., Reactions of aryl azides with a-keto phosphorus ylides, Tetrahedron, 1971, 27, 845-849. 

In substituted triazoles (obtained, for example, from phosphorus ylides and carbonyl-azides) H NMR is a valuable tool for determining the constituents and the progress of a reaction, as in the acyl group migration (34) (35) (70TL5225). In the case of the isomeric... 

L abbe and his collaborators have also demonstrated the importance of electronic effects in the synthesis of 1-vinyl-1,2,3-triazoles by adding azides ta either acetylenes (Eq. 15) or active methylene compounds (Eq. 16). In both cases iodoalkyl azides may be added, with comparable results, to produce precursors of 2.2-4 and 2.2-5. This very productive group has pioneered the excellent general method for l,5-disub tituted-l,2,3-triazoles involving phosphorus ylides (Eq. 17). The high yields and wide range of substituents employed makes this method most attractive. Product structures were demonstrated by the Dimroth addition and decarboxylation (Eq. 16). 

The preparation of N-acyl-1,2,3-triazoles by reaction of N-trimethylsilyl derivatives with acetyl chloride has been reported by Birkofer and Wegner (Eq. 1). In a later paper they showed that the 1-N-product (5.1-1) is obtained at low temperature (15°), and the 2-N-product (5.1-2) at high temperature (120°). The yields are generally high (ca. 90%), and the isomer ratio for an unsymmetrical case was determined (Eq. 2). Zbiral and his collaborators have added acetyl azide to a-keto phosphorus ylides and have obtained generally good yields of N-acetyl-1,2,3-triazoles (Eq. 3). The isomer ratio for unsymmetrical products (5.1-3) was not determined. 

The presence of an acyl group characterizes the second most common disubstituted 1,2,3-triazole and in general may be obtained in excellent yield from, for example, aroyl azides and phosphorus ylides (Eq. 31). A similar reaction has been used to prepare an acetyl-1,2,3-triazolecarboxylic acid... 

Several D-ribofuranosyl [113] and L-arabinofuranosyl 1,2,3-triazole derivatives [114] such as 119 have been prepared by cycloaddition of the corresponding glycosyl azide to 2-ethoxycarbonyl-2-oxoethylidene-triphenylphos-phorane, followed by reaction with methanolic ammonia or primary or secondary amines (Scheme 29). Some of prepared nucleosides proved to be potent inhibitors of HIV-1 replication. Phosphorus ylides containing an a-oxo group in the chain behave in a similar way as activated acetylenes with electron-donating groups [108[. Presimiably the azide adds to the enolate form of the ylide, followed by elimination of PhsPO [108]. 

Phosphorus Compounds. - The synthesis of the chiral phosphate (494) has been described. The silyl ether ds-Me3SiOCMe=CMeOSiMe3 reacts with Me0P(0)p3 to yield the dioxaphospholen (495). Treatment of the tetramer (496) with boron trifluoride affords the di-co-ordinated phosphorus compound (497). The imines (499) are obtained when the 1,2,3-diaza-phospholine (498) is heated with aryl azides. The oxazaphospholine (500) decomposes to trimethyl phosphate and the nitrile ylide (CF3)2C-N=CPh. ... 

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