Arylsulfonyl azide

Azidation.1 Arylsulfonyl azides generally react with enolates to effect net diazo transfer, but this hindered and electron-rich azide can effect azide transfer at the expense of diazo transfer. The nature of the enolate counterion also plays a role, with K being more effective than Na. In addition, acetic acid (or KOAc) is required as the quench for decomposition of the triazine intermediate to the azide with elimination of the arylsulfinic acid, ArS(0)0H. By use of these conditions, chiral N-acyloxazolidones such as 2 undergo diastereoselective azidation to give the azides 3 in 75-90% yield and in high optical purity (>91 9). These... 

The procedure most commonly used for the stereospecific preparation of optically active sulfoximides involves the reaction of optically active sulfoxides with arylsulfonyl azides in the presence of copper (98,118,131,178,179). This reaction occurs with retention of configuration at sulfur and with high stereospecificity. The stereospecific sulfoxide-sulfoximide conversion is a key reaction in the stereospecific sulfoxide-sulfimide-sulfoxiraide set of interconversions carried out by Cram and co-workers (98) and shown in Scheme 9. A similar cycle of interconversions studied independently by Andersen and co-workers (179) was used to determine the stereochemical course of the sulfoxide-sulfoximide transformation (see Scheme 10). 

Scheme 17.1 Copper-catalyzed decomposition of arylsulfonyl azides.

A few years ago an old reaction, that of the thermal decomposition of arylsulfonyl azides in pyridines, was re-examined (Scheme 42) (72JOC2022). Among the products identified was the 3-phenylsulfonamido derivative (96), which was proposed to arise by an electrophilic attack by phenylsulfonylnitrene. 

Cyclic a-diazo ketonesDiazo transfer can be conducted under phase-transfer conditions (tetra-n-butylammonium bromide or 18-crown-6) wth this arylsulfonyl azide. Other arylsulfonyl azides (mesityl, tosyl) are unsatisfactory. The method may not offer significant advantages with simple ketones, but is the most satisfactory route to hindered diazo ketones. Isolated yields in five cases were 48-84%. 

Although the addition of arylsulfonyl azides to enamines usually leads to amidines by loss of nitrogen from the intermediate triazoline adduct, when an electron-withdrawing substituent is present in the -position of the... 

Indoles (103), where R2R3 is a cyclic substituent, react with azides to give ring-contraction or -expansion products, depending on the arylsulfonyl azide and the solvent.499,502,503,512-517 Dihydroquinolines and dihydroiso-quinolines518 as well as indolizines519 show analogous behavior. 

Ring contractions are not frequent among the 5-alkoxytriazolines469,521 however, under pressure arylsulfonyl azides react with sterically congested silyl enol ethers to give clean one-carbon, ring-contracted products (Scheme 183).528 For example, cyclohexanone enol ethers give cyclopentanes in 62-87% yield. 

Zhang and coworkers reported recently that (porphyrin)cobalt(II) complexes are suitable for intramolecular amination of C-H bonds. Initially, ort/io-substituted arylsulfonyl azides 333a were subjected to 2 mol% of Co(TPP) 326a. Benzosultams 334a were formed in 87-99% yield (Fig. 80) [370]. When substrates... 

A novel synthesis of benzosultam 164 involves a Co-based catalytic system for intramolecular C-H animation with azides <07OL4889>. The commercially available cobalt tetraphenylporphyrin complex, Co(TPP) 163, is an effective catalyst for catalyzing C-H animation with arylsulfonyl azides 162 leading to benzosultams 164 in excellent yields. In addition to benzylic C-H bond, non-benzylic C-H bonds can also be intramolecularly aminated. For example, reaction of arylsulfonyl azides 165 with Co catalyst 163 results in a mixture of 5- and 6-membered ring products, 166 and 167. 

Thirupathi, N., Liu, X., Verkade John, G. Reactions of tris(amino)phosphines with arylsulfonyl azides product dependency on tris(amino)phosphine structure. Inorg. Chem. 2003, 42, 389-397. 

Diazoalkyl and Azidoalkyl Acids. - A convenient synthesis of dimethyl (diazomethyl)phosphonate involves the initial interaction of dimethyl (lithio-methyl)phosphonate and 2,2,2-trifluoroethyl trifluoroacetate, followed by further reaction with an arylsulfonyl azide. " The compounds (192) (R R = dialkyl or... 

A similar reaction with arylsulfonyl azides yields R2P(=N-S02Ar)X (X = Cl, OR, NH2, NHNH2, etc.). Secondary phosphines also react with silylazides, to form N-silylated imidoamino derivatives (Scheme 21). ... 

Polymer-bound arylsulfonyl azides have been tested as diazo transfer reagents (Roush et al., 1974 Diirr et al., 1981). Yields with diethyl malonate and acetylace-tone are slightly lower than those with 4-toluenesulfonyl azide. In contrast to these compounds with two neighboring activating groups, yields with monoactivated methylenes (ethyl propionate and cyclohexanone) are much lower. This method is therefore, not recommended in the described form. 

The diazo transfer reactions, discussed in the synthesis Sections 2.6-2.8 clearly indicate that arylsulfonyl azides and other compounds with the azido group act as electrophilic reagents, that add to nucleophiles, e.g., to C-anions of so-called active methylene compounds. This result is qualitatively easy to comprehend, since the N()8) and N(y)-atoms of the azides are electronically similar to the diazonio group, as shown in the mesomeric structures 4.20b-4.20c. 

General Considerations. The reactions of arylsulfonyl azides with enolates have been reported to give a range of products, depending on the fragmentation of the initial adduct. This may differ according to the nature of the enolate, the particular sulfonyl azide, and the quenching procedure. Net diazo transfer is usually observed for stabilized enolates, while azide transfer is more common with more reactive enolates. 

Regioselective ring expansion of alkynyl cyclopropanes to cyclobutenes has been reported via a copper-catalysed cycloaddition of an alkyne with an arylsulfonyl azide and a silver-catalysed carbene formation followed by ring expansion of a cyclopropyl carbene intermediate (Scheme 75)7° ... 

The reaction of Af-arylsulfonyl azides with terminal alkynes often leads to the formation of products resulting from rearrangement or loss of nitrogen, However, using copper iodide and 2,6-lutidine (1.2 equivalents) in chloroform at 0 °C affords the l-arenesulfonyl-1,2,3-triazoles 13". ... 

Under the usual conditions one equivalent of the diazoalkane is consumed by the liberated acid but this can be avoided by use of an added base such as triethylamine/ Cyclic a-diazoketones, which are not available from acid chloride, can be prepared by reaction of a nucleophilic derivative such as the a-hydroxymethylene enolate with arylsulfonyl azides. Several combinations of carbon nucleophile and sulfonyl... 

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