Sodium azide, reaction with azido-ketones

It is also possible to use amine surrogates in this type of reaction. When sodium azide reacted with the bromide moiety in 7.735 (see reaction 5), an a-azido-ketone was formed. This azide was reduced in situ to give ethyl 3-amino-4-oxopent-2-enoate, 1.136. ... 

The intramolecular 1,3-dipolar cycloaddition reaction of azides has become an increasingly useful process for the construction of natural products and molecules of theoretical interest.192 193 For example, 2-substituted azido enone (238) was prepared from the corresponding bromide by treatment with sodium azide. Thermolysis of this material afforded aziridinyl ketone (240) presumably via a transient dipolar cycloadduct (239).193 Ketone (240) was subsequently converted to an intermediate previously used to prepare histrionicotoxin (241 Scheme 56). 

Recently Zbiral and Stroh reported that treatment of a-azido-ketones (obtained generally by reaction of the a-halogenoketone with sodium azide) with triphenylphosphine is a convenient route to 2,5-disubstituted pyrazines (Scheme 5). Thus, 2,5-diphenyl-, 2,5-bis(4-methoxyphenyl)-, and 2,5-diisopropylpyrazine have been obtained in 75, 45, and 44% yield, respectively. The intermediate P-iV-ylide undergoes intermolecular condensation to give a 2,5-dihydropyrazine which is subsequently aromatized.122... 

Thermal decomposition of 3-azido-2-formylfuran, -thiophene, and -selenoles has also been used to prepare furo[3,2-c]isoxazole (97), thieno[3,2-c]isoxazole (4), and selenolo[3,2-c]isoxazoles (98) (Equation (27)) <76CS165>. In contrast, some azido ketones eliminate nitrogen at ambient temperature and cyclize as exemplified in the reactions of 2-chloro-3-acetylindole (99) (Equation (28)) and 3-chloro-2-benzoylbenzothiophene dioxide (101) (Equation (29)) with sodium azide (78CB1521, 92JOC2127). 

The reaction of alkenes with iodosobenzene in acetic acid in the presence of sodium azide offers a simple and high yield route to 1,2-diazides (Table 3)76. a-Azido ketones are side products or the exclusive product from the reaction with conjugated alkenes. Allylic azides or oxonitriles, resulting from oxidative cleavage of the C-C double bond, are alternatively obtained from trisubstituted steroid alkenes77. 

Azides are generally stable in the presence of bases and nucleophilic displacement of the azido group is uncommon, but displacements have been observed on a few vinyl azides. Reaction of j8-azidovinyl phenyl ketone 73 (R = H) with piperidine gave phenyl -2-piperidino-vinyl ketone (119) and reaction of the same azide with sodium hydroxide in aqueous methanol gave the dimethyl acetal 120 . 

The introduction of an azide functionality with CAN/NaNs as the reagents has been shown to be a useful transformation in organic synthesis. It also offers a convenient protocol for the bis-functionalization of a variety of alkenes. " The treatment of silyl enol ethers with sodium azide and CAN gives the a-azido ketones. The reactions of (substituted)styrenes with sodium azide and CAN in methanol under oxygenated conditions also furnish a-azido ketones (eq 21). With the aid of sodium iodide. 

This reaction was first reported by Corey and T.ink in 1992. It is an enantioselective synthesis of a -amino acids by means of the asymmetric reduction of trichloromethyl ketones from catechoiborane in the presence of either (/ )- or (5)-oxazaborolidine, followed by the treatment of the resulting alcohols with base and sodium azide and subsequently the reductive conversion of the azido group into an amino group. Therefore, this reaction is generally known as the Corey-Link reaction. Occasionally, it is also referred to as the Corey-Link amino acid synthesis, Corey-Link procedure, etc. 

After incubation of P-halo ketones with these genetically modified cells, addition of sodium azide resulted in most cases in the full conversion of the starting materials into the expected azido alcohols, isolated yields being comparable with those obtained with isolated enzymes. Moreover, this multienzymatic process was combined with a subsequent click reaction, that is, Cu(I)-catalyzed [2 + 3]-dipolar cycloaddition, allowing the one-pot preparation of the corresponding enantiopure P-hydroxytriazoles (Scheme 11.17b). 

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