Single azides

In the course of these studies, it was observed that the regioselective reduction of a single azide of multiple azide-containing molecules is feasible if only one equivalent of phosphine is used. Reduction of neamine derivative 23, for example, gave mono-amine 24 in a yield of 46 % (Scheme 16.8). Strong evidence was presented that the selectivity is primarily determined by electronic factors with electron-deficient azides being reduced more rapidly and efficiently than electron-rich azides. In compound 23 this is the case for... 

The preparation of amines by the methods described m this section involves the prior synthesis and isolation of some reducible material that has a carbon-nitrogen bond an azide a nitrile a nitro substituted arene or an amide The following section describes a method that combines the two steps of carbon-nitrogen bond formation and reduction into a single operation Like the reduction of amides it offers the possibility of prepar mg primary secondary or tertiary amines by proper choice of starting materials... 

The 1-mesyloxy intermediate (6) was similarly prepared via the equatorial monobenzoate, and it reacted with azide ion by a single SN2 displacement, since no anchimeric effect was possible here. The scyllo... 

The kinetics of many decompositions are conveniently studied from measurements of the pressure of the gas evolved in a previously evacuated and sealed constant volume system. It is usually assumed, and occasionally confirmed, that gas release is directly proportional to a, so that the method is most suitable for reactants which yield a single volatile product by the irreversible breakdown of a substance that does not sublime on heating in vacuum. A cold trap is normally maintained between the heated reactant and the gauge to condense non-volatile products (e.g. water vapour) and impurities. The method has found wide application, notably in studies of the decomposition of azides, permanganates, etc., and has been successfully developed as an undergraduate experiment [114—116]. 

The thermal decomposition reactions of KN3, T1N3, and AgN3 have been studied in the corresponding halide matrices [301]. The formation of NCCT from trapped C02 was described and labelling with ISN established that only a single end-N atom of the azide ion was involved in NCO formation. The photodecomposition of PbN6 and the effects of dopants have been followed [302] by the changes produced in the near and the far infrared. 

A diazo group can be introduced adjacent to a single carbonyl group indirectly by first converting the ketone to an a-formyl ketone (10-118), and then treating it with tosyl azide. As in the similar cases of 12-7 and 12-8, the formyl group is cleaved... 

In Reaction 12-9 treatment of Z—CH2—Z with tosyl azide gives diazo transfer. When this reaction is performed on a compound with a single Z group, formation of the azide becomes a competing process. " Factors favoring azide formation rather than diazo transfer include as the enolate counterion rather than Na orLi and... 

A gas ehromatographic analysis on the produet by the submitter, using an 0.3 x 80 cm. column packed with 10% silicone rubber (SE-30) supported on acid-washed, 60-80 mesh Chromasorb P at 80°, exhibited a single peak. The retention times of di-ter(-butyl malonate, di-fert-butyl diazomalonate, and p-toluenesulfonyl azide were 2, 6, and 9 minutes, respectively. The purity of the product obtained by the checkers was estimated from proton magnetic resonance spectra to be ca. 94%, the remainder being di-tert-butyl malonate. 

Treatment of 51 with an excess of sodium benzoate in DMF resulted in substitution and elimination, to yield the cyclohexene derivative (228, 36%). The yield was low, but 228 was later shown to be a useful compound for synthesis of carba-oligosaccharides. <9-Deacylation of228 and successive benzylidenation and acetylation gave the alkene 229, which was oxidized with a peroxy acid to give a single epoxide (230) in 60% yield. Treatment of 230 with sodium azide and ammonium chloride in aqueous 2-methoxyeth-anol gave the azide (231,55%) as the major product this was converted into a hydroxyvalidamine derivative in the usual manner. On the other hand, an elimination reaction of the methanesulfonate of 231 with DBU in toluene gave the protected precursor (232, 87%) of 203. 

DL-Valiolamine (205) was synthesized from the exo-alkene (247) derived from 51 with silver fluoride in pyridine. Compound 247 was treated with a peroxy acid, to give a single spiro epoxide (248, 89%) which was cleaved by way of anchimeric reaction in the presence of acetate ion to give, after acetylation, the tetraacetate 249. The bromo group was directly displaced with azide ion, the product was hydrogenated, and the amine acety-lated, to give the penta-A, 0-acetyl derivative (250,50%). On the other hand. 

Tetranitro derivative 94 (y-TACOT Section 12.10.15.5) treated with sodium azide in DMSO gives 83% yield of a single symmetrical diazido dinitro derivative 81 resulting from nucleophilic substitution of an equivalent pair of nitro groups by the azide anion (Equation 5) <1996JOC5801>. 

Group 13 azides as single-molecule precursors for nitrides 1041... 

There have been many other reports of single-source azido precursors, all aimed at achieving device-quality films using moderate deposition conditions. The azide precursors have the advantages of (i) having preformed Ga—N bonds and (ii) only a limited number of the undesirable Ga—C and N—C bonds which can lead to carbon incorporation into the nitride films.311 A list of azido-based precursors and deposition conditions is given in Table 14. 

In another application of coupling proteins to surfaces using click chemistry, Duckworth et al. (2006) carried out prenylation of a protein using a farnesyl azide derivative and the enzyme farnesyl transferase for subsequent chemoselective ligation to alkyne-functionalized agarose beads. The result is a highly discrete, site-specific attachment of the protein to the solid phase at a single location. 

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