Azides, arenesulfonyl

A polymer bound arenesulfonyl azide can be prepared from polystyrene.138... 

Nitrenes can be generated from many precursors such as azides, isocyanates, ylides, heterocycles, and nitro compounds.236,237 Amongst these, azides are the most convenient precursors since they are easily prepared and can be decomposed by heat, light or a suitable catalyst. Despite considerable endeavors, no one has yet provided a synthetically viable method to use azides as sources of nitrenes.237 The breakthrough of nitrene chemistry was the recognization of the value of A-arenesulfonyl iminoiodinanes (ArS02N=IPh) as nitrene precursors by Breslow and Mansuy. - They reported inter- and intramolecular C-H insertions by tosylimino phenyl-iodinane (TsN=IPh) in the presence of Mn(m) or Fe(m) porphyrins or [Rh2(OAc)4]. Subsequently, Muller... 

The HC1 generated in this reaction destroys one equivalent of diazomethane. This can be avoided by including a base, such as triethylamine, to neutralize the acid.74 Cyclic z-diazoketones, which are not available from acyl chlorides, can be prepared by reaction of an enolate equivalent with a sulfonyl azide. This reaction is called diazo transfer 5 Various arenesulfonyl azides76 and methanesulfonyl azide77 are used most frequently. Several types of compounds can act as the carbon nucleophile. These include the anion of the hydroxymethylene derivative of the ketone78 or the dialkylaminomethylene derivative of... 

JV-Alkoxycarbonyl- and iV-arenesulfonyl-imines can be prepared by the reaction between pyridines and nitrenes, the latter being generated from the corresponding azides (72JOC2022, 64TL1733). Thermolysis of pyridinium iV-acylimines gives isocyanates and the parent heterocycle <79JCS(P1)446). 

As part of a study of the reactions of arenesulfonyl azides with indoles, Bailey et al.lu obtained a compound from the action of tosyl azide on indoline-2-thione to which they ascribed structure 114 (R = H). In contrast, N-methylindoline-2-thione gave only a low yield of 114 (R = Me) under the same conditions. Diazo-transfer via an intermediate 115 is thought to be involved when R = H, facile loss of toluene-p-sulfonamide leads to 114a, but when R = Me, loss of the same fragment leads mainly to other products. 

Various nucleophilic attacks at C(3) and C(4) of -lactams have been employed to introduce desired functionalities. Nucleophilic displacement of a halogen at C(3) by nucleophiles, for example, potassium phthalimide, has been performed (93JCS(Pl)2357). The a-azidation of l-hydroxy-2-azetidi-nones, for example (37), with arenesulfonyl azides in the presence of triethylamine affords 3-azido-2-azetidinones (38) via Otosylation and SN2 -type of displacement of the tosyloxy group (92JA2741, 93JA548, 93BMC2429). 

The nitrogen source for the aziridination of alkenes, a nitrene or nitrenoid, can be generated in various ways (1) oxidation of a primary amine (2) base-induced -elimination of HX from an amine or amide with an electronegative atom X (X = halogen, O) attached to the NH group or by -elimination of metal halides from metal A-arenesulfonyl-A-haloamides (3) metal-catalyzed reaction of [A-(alkane/arenesulfonyl)imino]aryliodanes (4) thermolytic or photolytic decomposition of organyl azides and (5) thermally induced cycloreversion reactions . 

The reactions of arenesulfonyl isothiocyanates 24 with azides give thiatriazole derivatives... 

Several alkyl and aryl azides have been reduced to the corresponding amines in good yield by tin(II) chloride at room temperature the less reactive azides require a catalytic amount of aluminum trichloride to be added. Aqueous vanadium(ll) chloride is a useful reducing agent for aryl azides heteroaryl and arenesulfonyl azides have been reduced with aqueous titanium(lll) chloride and with a molybde-num(III) catalyst generated from molybdenum(V) chloride and zinc. ... 

Aromatic sulfonyl azides react with enol ethers of cyclic ketones to form arenesulfonyl imidate esters (96) with ring contraction, the addition-rearrangement process is very stereospecific (Scheme 63). 

Sulfonyl Azides. Alkyl- and arylmagnesium halides,305 306 as well as alkyl-307, aryl- (see Eq. 70),308-312 and heteroaryllithium313 reagents add to sulfonyl azides to give triazene salts which may be reduced to amines 305 310 312 Gr converted into azides. The latter reaction has been accomplished by an aqueous workup with the highly hindered 2,6-dimesitylphenyl azide,314 whereas quenching with aqueous potassium hydroxide (see Eq. 72)305,315 sodium bicarbonate,313 or sodium pyrophosphate305,316 (see Eqs. 67 and 74) is necessary with other arenesulfonyl azide adducts. Thermolysis of the dry triazene salts also leads to azides,307,308 but because of the hazards involved, this procedure is not recommended. 

Ketene dimethyl acetals react with phenyl azide to give a-anilido esters after acid hydrolysis of the intermediate triazolines, but yields are low.291 The reaction of ketene acetals with arenesulfonyl azides does not appear to have been investigated. 

This reaction is arguably the most useful and certainly the most widely used application of the electrophilic C-amination of enolates in organic synthesis. A number of 4- and 4,5-substituted 2-oxazolidinones are commercially available in both enantiomeric forms and the chiral auxiliary is easily recovered.430 Reactions of A-acyloxazolidinonc enolates with azo esters431,432 and arenesulfonyl azides433 are rapid even at very low temperatures (—100°) and the diastereochemical outcome is reliably predictable. The facile removal of the chiral auxiliary and ready conversion of the azide or hydrazino ester functionalities into amines makes these reactions a standard method for the preparation of d- and L-a-amino acids. 

Diphenylphosphinoyl)hydroxylamine (Eq. 137),143 azo esters (Eq. 138),460 and arenesulfonyl azides (Eq. 139)339 have been used to aminate lactam enolates. In the azidation of the lactam 70,461 the diazo compound 73 predominates over azide 72 even though trisyl azide is used as the animating agent amination with di(ferf-butyl) azodicarboxylate was unsuccessful. The closely related lactam 71462 reacts normally with trisyl azide (Eq. 140). 

Enolates of (3-dicarbonyl and a-cyanocarbonyl compounds have a strong tendency to form diazo compounds with arenesulfonyl azides. a-Substituted substrates react normally to give azides482 483 but even then a diazo transfer (Eq. 166)484 or other transformations319 321 484 may occur as side reactions. 

Nitrenes generated photochemically or thermally from arenesulfonyl azides and alkoxycarbonyl azides add to the nitrogen atom of heteroaromatic bases to give the corresponding N-(substituted imines).20,21,50,64-69 However, the yields are usually low and the scope is severely limited. 

Arenesulfonyl azides react at ambient pressure with enol ethers of simple cyclic ketones to give ring contracted arenesulfonylimidate esters in good yields (equation 99)90. The addition-rearrangement is highly stereoselective as shown in equations 100-102. 

Under special conditions (addition of lithium amide, phase-transfer catalysis), compounds with apparently unactivated methylene groups (e.g., 5-methoxy-l-tetra-lone, Lombardo and Mander, 1980) or even with a methyl group at an arylcarbonyl group (Sugihara et al., 1987) undergo diazo transfer with arenesulfonyl azides. This is also the case for esters of 4-arylbut-3-enoic acid and related compounds (Davies et al., 1989, and references therein). 

For other arenesulfonyl azides used for diazo transfer, see Houben-Weyl (Klamann and Hagemann, 1990, p. 1054). 

In the isolation and crystallization of these equilibrium mixtures it is interesting that, with the exception of the last two entries in Table 2-3, the crystallization equilibria are on the side of the triazole. This is also the case for the reaction of arenesulfonyl azides with ethoxyacetylene (Scheme 2-86), although in solution the a-diazoimidate 2.220 is strongly favored. 

The regioselectivity of addition of arenesulfonyl azides and cyanogen azide to strong donor-substituted alkynes is high, but low with alkyl and aryl azides. These azides of low electrophilicity are not, however, useful for the synthesis of diazo compounds, as the triazole form can be cleaved only in rare cases. 

Heating arenesulfinyl azides in DMSO affords arenesulfonyl sulfilimines (154). The results are consistent with nitrene trapping followed by rearrangement. 

The existing alternative preparative methods for the a diazo esters, such as diazotization of glycine esters, p3TolysIs of TYacylYVnltrosoglydne esters, hase-catalyzed cleavage of 0 dlazo ketoacetates, reactions of alkoxycarhonylmethylene phosphoranes with arenesulfonyl azides, or add catalyzed decomposition of acetic esters with aryltriazene substituents, all... 

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