2-azido- -imidates

In 1999, Jacobsen and Myers reported catalytic enantioselective 1,4-addition of HN3 to a,p-unsaturated imides catalyzed by Al(salen) catalysts (Scheme 6.90). In the presence of 5-10mol% of MeAl[(S,S)-salen] (67c), the reaction of N-benzoyl crotonamide and an excess amount of HN3 gave p-azido imides in high yield with excellent enantioselectivity. Al[(S,S)-salen]N3, which was rapidly generated from the reaction of MeAl[(S,S)-salen] and HN3, was proposed as an active catalyst species. According to kinetic studies, it was confirmed that Al[(S,S)-salen]N3 does not act as an azidation reagent but as a Lewis acid catalyst. 

The Zn-N3imide interaction has been used to selectively extract imide-containing nucleosides and nucleotides into lipophilic media (39). Hexadecyl-derivatized Zn2+-cyclen was shown to extract dT from an aqueous solution containing a mixture of C, A, and G nucleobases. The antiviral agent AZT (3 azido-3 deoxythymidine) could also be extracted into CHCI3 from neutral aqueous solutions. Transport across a lipophilic layer was also shown, using acidic conditions, to promote the release of dT and AZT (Fig. 9). 

Die zweistufige Reduktion von Azido-Verbindungen iiber Phosphan-imide eignet sich u. a. auch zur Herstellung von C-Amino-H-heteroarenen (z. B. 4-Amino-6-chlor-3-phenyl-pyri-daziri) aus C-Azido-N-heteroarenen2. 

Azido-6-nitro l,4 benzoquinone-4-trimethyl-imide or Tri methyl-[3-axi do-5-nitro 4-hydroxy-phenylj-ammonium Hydroxide,... 

Organic Amides and Imides A170 Al7l Organic Azides and Azido Derivatives A626 to A643... 

Trimethyl-[3-azido-5-nitro-4-hydroxy phenyl]-ammonium Hydroxide. See 2-Azido-6-nitro-1,4-ben zoquinone-4-trimethyl imide A640-R... 

Auch aliphatische Azide (z.B. Methyl-, Ethylazidl75, Trifluormethylazid176, 2-(2-Azido-ethyl)-pyridin177) sowie Azido-l,3,5-triazine178 reagieren unter Bildung entsprechender Phosphorsaure-imid-triester (40-99%) ... 

This hydrolysis of the chiral imide auxiliary in the presence of other potentially vulnerable ester groups has proved to be very successful. A lucid example is given in the synthesis of the cyclic tripeptide OF4949-III 14. The complex a-azidocarboximide 11 is transformed into the corresponding a-azido acid 12 by means of lithium hydroperoxide in 89% yield. 

The block synthesis strategy is demonstrated here by the synthesis of the dimeric-Lewis octasaccharide (29) described by Schmidt and coworkers [8,9]. As shown in the retrosynthetic analysis (Scheme 5.5), the octasaccharide (29) should be accessible from the tri- (30) and disaccharide (31) units, represented by the blocks 32 and 33. The trisaccharide block can be disconnected from the L-fucosyl (34) and D-galactosyl (35) imidates and the 2-azido-2-deoxy-o-glucose derivative (36). 

Evans, D. A., Britton, T. C., Ellman, J. A., Dorow, R. L. The asymmetric synthesis of a-amino acids. Electrophilic azidation of chiral imide enolates, a practical approach to the synthesis of (R)- and (S)-a-azido carboxylic acids. J. Am. Chem. Soc. 1990, 112, 4011-4030. 

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