Azides, reaction with anhydrides

The reaction of anhydrides with aryl azides, in the presence of McaSiCl and Nal, gives N-aryl imides. 

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. 

Enantiomerically pure tripeptide aldehydes are typically synthesized by azide or mixed anhydride coupling of dipeptides to a-amino aldehydes or their semicarbazone derivatives. For example, Ac-Leu-Leu-Phe-H was synthesized by the azide coupling of Ac-Leu-Leu-OH with Phe-H semicarbazone, prepared by catalytic hydrogenation of Z-Phe-H semicarbazone. The tripeptide semicarbazone was deprotected with 37% HCHO/HC1 solution (Table 2)J5 C-terminal argininal, ornithinal, and lysinal peptides such as Z-Leu-Leu-Orn(Boc)-H and Z-Leu-Leu-Lys(Boc)-H were prepared by mixed anhydride coupling of Z-Leu-Leu-OH with Orn(Boc)-H semicarbazone or Lys(Boc)-H semicarbazone. 3 Z-Leu-Leu-Arg(N02)-H was prepared by mixed anhydride coupling of Z-Leu-Leu-OH with Arg(N02)-H semicarbazone trifluoroacetate, prepared from the reaction of TFA and Boc-Arg(N02)-H semicarbazone (Table 2) J31... 

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). 

The reaction of nitrido(5,10,15,20-tetramesity]porphyrinato) manganese(V) (TMPMn = N), obtained by photolysis of the azide (TMPMnN,) with excess trifluoroacetic anhydride, afforded, in situ, the trifluoroacetylimidomanganese(V) trifluoroacetate which reacted with cyclooctene to give the corresponding AT-trifluoroacetyl aziridine l97. 

While S n reactions of the anhydride group are common, Sy reactions of substrates in which the anhydride group activates an aromatic ring are rarely reported. It is of interest therefore that 3-azidophthalic acid and tetrazidophthalic acid have been obtained by reaction of azide ion with 3-nitro- and tetrachloro-phthalic anhydride respectively . 

Hie cyclic anhydride (80.4) reacts with trimethylsilyi azide under anhydrous conditions to give a mixture of I,3-oxazine-2,6-dione isomers, which was used without further purification to synthesis several extended purines. Reaction with formamidine acetate in DMF in effect replaced the furandione ring by a pyrimidinone. Cyanamide produced a new fiued 2-aminopyrimidin-4-one [in (80.5, R = NH )], while urea led to a pyrimidinedione. Isatoic anhydride similarly yields 2-aminoquinazolin-4-one on treatment with cyanamide-DMF. 

For reaction with azides, amides can be activated with trifluoromethanesulfonic anhydride or benzo-triazole, or via formation of the thioamide, or by the use of triphenylphosphine with diethyl azodicar-boxylate. Alternatively, imidochlorides can be used under phase-transfer conditions. ... 

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