Azido derivatives

Treatment of the diazonium salts with sodium azide yields azido derivatives (93HAC521, 93IZV1949, 93RCB1865, 94HAC441, 96ROC734, 96ZOR766). 

Thermolysis of the azido derivative 143 (R = R =H) in refluxing 1,2-dichlorobenzene gave the pyrroloquinoline 144 and the dihydropyrrolo derivative 145 amongst other products (79H1021), whereas its thermal... 

Several 5,6-disubstituted-3-azido[l,2,4]triazine-l-oxides 1021 were prepared (77JHC1221) by treatment of 1020 with nitrous acid. 3-Azido[l, 2,4]-triazine-2-oxide 1023 was prepared by reacting the corresponding 3-bromo derivative 1022 with either tetramethylguanidinium azide in chloroform or sodium azide in aqueous acetone. These azido derivatives were proven to exist in the open-chain form by H- and l3C-NMR and 1R spectra (77JHC1221) (Scheme 191). 

Figure 17.12 Azido derivatives of sugars can be used as monomers for glycan and carbohydrate synthesis by cells. Such modifications can be probed using click chemistry or Staudinger ligation reactions.

Azido derivatives of furazans have proved to be particularly useful for the synthesis of heterocyclic systems. Thus, by 1,3-dipolar addition of l-azido(4-amino-l,2,5-oxadiazol-3-yl)aldoxime 186 to propargyl alcohol and phenylacetyl-ene, bicyclic 4-amino-l,2,5-oxadiazol-3-yl(4-R-l,2,3-triazol-l-yl)ketoximes 187 were obtained (Equation 34) which in reaction with acetic anhydride afforded the corresponding 0-acyl derivatives <2003RJ0574>. 

The enhanced reactivity of 5-halogeno-l,2,4-thiadiazoles over 3-halogeno-l,2,4-thiadiazoles has been mentioned before (see Section 5.08.7.1). Nucleophilic substitution at this center is a common route to other 1,2,4-thiadiazoles, including 5-hydroxy, alkoxy, mercapto, alkylthio, amino, sulfonamido, hydrazino, hydroxylamino, and azido derivatives. Halogens in the 3-position of 1,2,4-thiadiazoles are inert toward most nucleophilic reagents, but displacement of the 3-halogen atom can be achieved by reaction with sodium alkoxide in the appropriate alcohol <1996CHEC-II(4)307>. 

The aryl azido derivatives of [32P]NAD+ were employed to site-specifically incorporate photoactivatable ADP-riboses to transducin at Cys-347 by means of pertussis toxin, and the conjugation was followed by irradiation. Photocrosslinking revealed three major bands after irradiation which corresponded to a-y(47 kDa), a-a (83 kDa),and a-a-a (105kDa) subunit contact domains [88]. 

In the course of studies on azide-tetrazole equilibria, some azido derivatives 73 of this ring system have been subjected to X-ray structure elucidation <2005JST(751)65>. These derivatives proved to be mainly planar and the least planar part of these molecules were the azide moieties. In both cases (72 R= H and Me), formation of hydrates were also observed. Crystallographic analysis of the trifluoromethyl compound was described by Lange et al. <1997APH299>, and structure elucidation of the nucleoside analogue 74 was reported by Stanovnik et al. <1998JHC513>. 

Thus, 5-methoxypyrimidine 103 when treated with lithium tetramethylpiperidide (LTMP) and subsequently by tosyl azide led to formation of the 2-azido derivative 104, which spontaneously undergoes ring closure to 8-methoxytetrazolo[l,5-c]pyrimidine 105. 

The bromodeoxyaldonolactones have been used for the preparation of aminodeoxy aldonic acids and aminodeoxy sugars via azido derivatives (45,46). Likewise, a- and /J-aminopolyhydroxy acids have been prepared by treatment of the bromodeoxyaldonolactones with liquid ammonia (47). Thus, 3-amino-3-deoxy-D-threonic acid and 3-amino-3-deoxy-D-arabin-onic acid (40b) were obtained from 2-bromo-2-deoxy-L-threono- or D-xy-lono-1,4-lactone (38). It was shown that 2,3-epoxy carboxamides (namely, 39) are intermediates of the reaction. Heating at 90° for long periods led to the 3-amino-3-deoxyaldonamides, which upon acid hydrolysis yielded the corresponding aldonic acids. 

In order to construct the L-asparagine derivative of per-O-acetylated 0-(2-acetamido-2-deoxy-/ -D-glucopyranosyl( 1 — 4)-2-acetamido-2-deoxy-D-glucose (7), Spinola and Jeanloz (13) used (the sensitive) silver azide for conversion of the a-chloro anomer of the chitobiose derivative 8 into the / -azido derivative 9. Kunz and associates (14,15) have accomplished the conversion of the a-chloro anomer of 8 into 9 using sodium azide in the presence of tri-n-octyl-methylammonium chloride as a phase-transfer catalyst in chloroform water. 

The triazolotriazole (13) has been prepared by cyclization of an azido derivative (Scheme 37). °... 

HIGH-ENERGY, HIGH-DENSITY. POLYCYCLIC HYDROCARBONS AND AZIDO DERIVATIVES... 

Reduction of Nitro, Nitroso, Diazo and Azido Derivatives... 

REDUCTION OF NITRO, NITROSO, DIAZO AND AZIDO DERIVATIVES OF HYDROCARBONS AND BASIC HETEROCYCLES... 

Reductions of halogen, nitro, diazo and azido derivatives of esters resemble closely those of the corresponding derivatives of carboxylic acids (p. 141). 

Various nitrosoarenes have been utilized as benzofurazan precursors including o-azido derivatives generated from the o-chloro analogues <66JCS(B)1004>, and 1-amino-2-nitrosoarenes which can be oxidized with ferricyanide or hypochlorite. Treatment of o-nitrosophenols with hydroxylamine also affords the furazan, presumably via an oximation-dehydration pathway involving the tautomeric o-quinone monooxime. Other related approaches involve the reduction of o-dinitroarenes with borohydride, and the thermolysis of o-nitroanilines and o-nitroacetanilides. 

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