Sodium azide, reaction with anhydrides

Hendrickson synthesized allyl triflones using tetrabutylam-monium triflinate. The quaternary ammonium system is more soluble and 20-40 times more reactive than the conventional potassium triflinate. Tetra-n-butylammonlum azide (6) prepared from tetra-/3-butylammonium hydroxide and sodium azide reacts with triflic anhydride in chloroform at —78°C to give a 1 1 mixture of tetrabutylammonium triflinate (7) and tetrabutyl-ammonium triflate (8). Treatment of this mixture with allyl bromide gives the corresponding allyl triflone (5) in almost quantitative yield. The water-soluble triflate coproduct (8) in the reaction mixture does not interfere with the formation of (5), which is readily Isolated (eq 4). 

Another nittogen-containing inflate derivative, trifluoromethanesuifonyi azide, IS prepared by the reaction of triflic anhydride with aqueous sodium azide [775] and IS used as an efficient reagent for the synthesis of alkylazides from alkylanunes (equation 58)... 

Treatment of N-benzoyl-L-alanine with oxalyl chloride, followed by methanolic triethylamine, yields methyl 4-methyl-2-phenyloxazole-5-carboxylate 32 <95CC2335>. a-Keto imidoyl chlorides, obtained from acyl chlorides and ethyl isocyanoacetate, cyclise to 5-ethoxyoxazoles by the action of triethylamine (e.g.. Scheme 8) <96SC1149>. The azetidinone 33 is converted into the oxazole 34 when heated with sodium azide and titanium chloride in acetonitrile <95JHC1409>. Another unusual reaction is the cyclisation of compound 35 to the oxazole 36 on sequential treatment with trifluoroacetic anhydride and methanol <95JFC(75)221>. 

The aziridine aldehyde 56 undergoes a facile Baylis-Hillman reaction with methyl or ethyl acrylate, acrylonitrile, methyl vinyl ketone, and vinyl sulfone [60]. The adducts 57 were obtained as mixtures of syn- and anfz-diastereomers. The synthetic utility of the Baylis-Hillman adducts was also investigated. With acetic anhydride in pyridine an SN2 -type substitution of the initially formed allylic acetate by an acetoxy group takes place to give product 58. Nucleophilic reactions of this product with, e. g., morpholine, thiol/Et3N, or sodium azide in DMSO resulted in an apparent displacement of the acetoxy group. Tentatively, this result may be explained by invoking the initial formation of an ionic intermediate 59, which is then followed by the reaction with the nucleophile as shown in Scheme 43. 

The acyl azide intermediates are prepared either by reaction of sodium azide with a reactive acylating agent or by diazotization of an acyl hydrazide. An especially convenient version of the former process is treatment of the carboxylic acid with ethyl chloroformate to form a mixed anhydride, which then reacts with azide ion.265... 

Goodman and Chorev 75 found that the required a-aminoacyl azides 14 are best prepared by reaction of the mixed anhydride of the amino acid with sodium azide. This method led to slightly better yields than the nitrosylation of TV-formylaminoacyl hydrazide. Curtius rearrangement of the a-aminoacyl azide 14 yielded the isocyanate 16, which was subsequently trapped as 17 or 18 as shown in Scheme 2. Comparable yields were obtained by nitrosylation with tert-butyl nitrite. 76 Other methods of acyl azide formation have rarely been employed for PMRI-peptide synthesis. Only Fincham et al. 11 reported the use of trimethylsilyl azide to synthesize an acyl azide en route to a PMRI-peptide. 

Several different nucleophilic displacement reactions of ring substituents were utilized in the synthesis of 3-azido-oxetane-2-carboxylates (Scheme 12) <2001TL4247>. The triflate ester 66, prepared from the corresponding trans-/3-hydroxy ester and triflic anhydride, was displaced by reaction with sodium azide, and inversion of configuration, to... 

The reaction of compound (86) with hydroxylammonium chloride in acetic anhydride in the presence of pyridine gave the corresponding cyano-substituted compound (252). Alkaline hydrolysis of compound (252) gave the diacid (253), and reaction with sodium azide and ammonium chloride in DMF led to the tetrazole (254). The compounds (8i), (82), (84), (85), and (87) reacted similarly <93CCC2139, 94MI 701-01). 

Reaction of the benzodioxocine 170 with the epoxidation reagent resulted in the epoxide 171, which was then opened with sodium azide in situ to provide trans-racemic azide 172 (Scheme 18) <2004MI265>. Reduction of the azide 172 by hydrogenolysis using Pd on carbon gave trans-racemic amine 173 in 70% yield over three steps. On acylation of the amine with acetic anhydride, the trans-racemic alcohol 174 was formed, which was then oxidized with Dess-Martin periodinane into the unstable dioxocinone 175. 

Treatment of phthalic acid (145) with sodium azide under acidic conditions has been reported" to give various products anthranilic acid (147) and a trace of o-phenylenediamine (148) in concentrated sulfuric acid and anthranilazide (149) and benzimidazol-2-one (150) in 90% sulfuric acid. Analogously, phthalic anhydride (146) gives the following products anthranilic acid (147), benzimidazol-2-one (150) and some 3,l-benzoxazine-2,4(l//)-dione (isatoic anhydride) (151) in sulfuric acid and benzimidazol-2-one (150) in acetic acid. A recent report" has revealed that Ae Schmidt reaction of phthalic acid (145) in 90-98% sulfuric acid gives anthranilic acid (147) and anthranilazide (149) (major products) by a process thought to involve 3,l-benzoxazine-2,4(l//)-dione (151) as an intermediate. Benzimidazol-2-one (150) is produced in this reaction by a secondary process from anthranilazide (149). Photolysis of (149) also produces (150). 

The Curtius rearrangement has been extensively utilized for the synthesis of numerous cyclo-propylamines 4 from cyclopropanecarboxylic acids 1. The necessary acyl azides 2 are most conveniently obtained by reaction of sodium azide with the mixed anhydride of the cyclopropanecarboxylic acid and ethyl chloroformate. ... 

The use of acetic anhydride as the solvent facilitates432 intermolecu-lar iodide displacements at C-5 of 156. Acylation of the heterocyclic base occurred at N-l (as indicated by infrared spectroscopy) during the reaction, and this inhibited occurrence of intramolecular displacement. The electron-withdrawing effect of the acyl group presumably diminishes the nucleophilicity at N-3. N-Formyl-2, 3 -0-iso-propylidene-5 -0-p-tolylsulfonyladenosine also reacts intermolecu-larly with lithium chloride or sodium azide in methyl sulfoxide to give 5 -chloro and 5 -azido derivatives.432... 

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