Reactions sulfonyl azides

A comprehensive review of reactions of isocyanates and 1,3-dipolar compounds has been previously pubhshed (51). The example shown illustrates the reaction of azides and isocyanates to yield tetrazoles (14,R = alkyl or aryl, R = aryl or sulfonyl) (52,53). 

Further studies revealed that the yields of l//-azepines could be increased substantially by carrying out the thermolysis of the sulfonyl azide in a nitrogen atmosphere under pressure.62-158159 For example, thermolysis of tosyl azide in benzene at 155-160 C and a nitrogen pressure of 11.5 atmospheres produced l-tosyl-l//-azepine in 5% yield, which rose to 48% under a nitrogen pressure of 82-89 atmospheres.158 The reaction temperature was critical as no azepine was formed at 140-145°C-regardless of the nitrogen pressure.160... 

Mg or Ca in MeOH, " baker s yeast, Sm/l2, LiMe2NBH3, and tin complexes prepared from SnCl2 or Sn(SR)2. This reaction, combined with RX —+ RN3 (10-65), is an important way of converting alkyl halides RX to primary amines RNH2 in some cases the two procedures have been combined into one laboratory step. Sulfonyl azides (RSO2N3) have been reduced to sulfonamides (RSO2NH2) by irradiation in isopropyl alcohol and with NaH. ... 

Besides short ELPS, longer ELPs have also been conjugated to synthetic polymers. In one approach, Cu(I)-catalyzed azide-alkyne cycloaddition click chemistry was applied. For this purpose, ELPs were functionalized with azides or alkynes via incorporation of azidohomoalanine and homopropargyl glycine, respectively, using residue-specific replacement of methionine in ELP via bacterial expression [133]. More recently, an alternative way to site-selectively introduce azides into ELPs was developed. Here, an aqueous diazotransfer reaction was performed directly onto ELP[V5L2G3-90] using imidazole-1-sulfonyl azide [134]. 

Sulfonylnitrenes are formed by thermal decomposition of sulfonyl azides. Insertion reactions occur with saturated hydrocarbons.255 With aromatic compounds the main products are formally insertion products, but they are believed to be formed through addition intermediates. 

The direct, stereoselective conversion of alkynes to A-sulfonylazetidin-2-imines 16 by the initial reaction of copper(l) acetylides with sulfonyl azides, followed, in situ, by the formal [2+2] cycloaddition of a postulated A-sulfonylketenimine intermediate with a range of imines has been described <06AG(E)3157>. The synthesis of A-alkylated 2-substituted azetidin-3-ones 17 based on a tandem nucleophilic substitution followed by intramolecular Michael reaction of primary amines with alkyl 5-bromo-4-oxopent-2-enoates has been... 

Decomposition of sulfonyl azides was shown to be catalyzed by copper in 1967 (72, 73). In the presence of alkenes, the reaction provides both aziridines and the C-H insertion products, albeit in low yields (73). In 1991, Evans et al. (74, 75) illustrated that both Cu(I) and Cu(II) salts were effective catalysts for nitrenoid transfer from [A-(/Moluenesulfonyl)imino]phenyliodinane (PhI=NTs) to a variety of acceptor alkenes. In the absence of ancillary ligands, reactions proceed best in polar aprotic solvents such as acetonitrile. Similar results are observed using both Cu(MeCN)4C104 and Cu(acac)2 as precatalysts, Eq. 53. 

A reaction known as diazo group transfer produces diazo barbituric acid from barbituric acid and p-toluene sulfonyl azide. Additional barbituric acid affords azo barbituric acid [7]. Subsequent complexation with a nickel (II) salt yields a greenish yellow pigment. 

Bis-acceptor-substituted diazomethanes are most conveniently prepared by diazo group transfer to CH acidic compounds either with sulfonyl azides under basic conditions [949,950] or with l-alkyl-2-azidopyridinium salts [951] under neutral or acidic conditions [952-954]. Diazo group transfer with both types of reagents usually proceeds in high yield with malonic acid derivatives, 3-keto esters and amides, 1,3-diketones, or p, y-unsaturated carbonyl compounds [955,956]. Cyano-, sulfonyl, or nitrodiazomethanes, which can be unstable or sensitive to bases, can often only be prepared with 2-azidopyridinium salts, which accomplish diazo group transfer under neutral or slightly acidic reaction conditions. Other problematic substrates include amides of the type Z-CHj-CONHR and P-imino esters or the tautomeric 3-amino-2-propenoic esters, which upon diazo group transfer cyclize to 1,2,3-triazoles [957-959]. 

When 2-alkyl-3-keto esters or 2-aryl-3-keto esters are treated with sulfonyl azides under basic conditions, nucleophilic deacylation occurs to yield 2-alkyl/aryl-2-diazo esters [960-963]. Nucleophilic deacylation can also be used to convert acceptor-substituted diazoketones into the corresponding acceptor-substituted diazomethanes [964,965]. In all these deacylation reactions it is the most electrophilic carbonyl group which is attacked by the nucleophile and cleaved off. 

Sulfonyl azides are exceptional in that they do not normally give triazoles with activated methylene compounds nucleophilic attack by the carbanion is usually followed by loss of the sulfonamide anion, giving a diazo compound as the product. Possible mechanisms for the reaction are illustrated (Scheme 8) for diethyl malonate. Attack of the carbanion on the terminus of the azide gives the anion of the linear triazene (1). 

Closure to the triazoline certainly occurs in many systems, since products are isolated which can only have been formed by this route. Occasionally these products include w-triazoles for example, 4-phenyl-triazole is isolated in moderate yield from the reaction of the aldehydes (3) with toluene-p-sulfonyl azide (Scheme 9). ... 

The reaction is most effective with azides bearing electron-withdrawing groups, such as nitrophenyl, toluene-p-sulfonyl, and ethoxy carbonyl. Sulfonyl azide adducts give iV-unsubstituted triazoles, the substituent being lost on aromatization. The triazole which is isolated as a minor product of the reaction of 1,1-dimethoxyethylene with ethoxycarbonyl azide has been assigned a 2/7-triazole structure it is likely that other ethoxycarbonyltriazoles formed by this route also have 2H-structures. 

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... 

In addition to previously described syntheses4-5 by diazo group transfer with deformylation,6 2-diazocyclohexanone has been prepared by two variants of this method. In one, the reaction of 2-(hydroxymethylene)cyclohexanone with -toluene-sulfonyl azide is carried out in ether/diethylamine, and an enamine is assumed to be formed as an intermediate 7 in the other, the sodium salt of the hydroxymethylene compound was treated with the lithium salt of p-carboxybenzenesulfonyl azide... 

A mixture of sulfonyl-azafulleroid 168 and sulfonylaziridino-fullerene 169 was obtained by reaction of sulfonyl azide with CgQ in o-dichlorobenzene at 160 °C (Scheme 4.30) [173]. The ratio of the two products depends on the substituent of the sulfonyl group. In all cases the aziridino fullerene can be obtained from the azafulleroids by irradiation. 

A primary or a secondary amine can be protected by reaction with phenacyl-sulfonyl chloride (PhC0CH2S02Cl) to give a sulfonamide RNHS02CH2C0Ph or R2NS02CH2C0Ph.1741 The protecting group can be removed when desired with zinc and acetic acid. Sulfonyl chlorides react with azide ion to give sulfonyl azides RSO-.N3.1742 OS IV, 34, 943 V, 39, 179, 1055 VI, 78, 652 VII, 501 69, 158. See also OS VI, 788. 

Sulfonyl azides react with pyridine to give pyridine 1-sulfonylimides (e.g. 367). However, the analogous reaction with 2,4,6-trimethylpyridine gives some 3-(phenylsulfonylamino) derivative together with the 1-sulfonylimide. Nitrenes derived from photolysis of acyl azides also add to the nitrogen atom to form the corresponding pyridine A-imines (74AHC(17)220). 

Nitrene intermediates are formed in the thermal decomposition reactions of most alkyl azides, aryl azides, sulfonyl azides, and azidoformates. Some decompositions, however, must be regarded as proceeding by a synchronous mechanism. They are discussed in this section. 

To compare the reactivity of different classes of organic azides, the region is determined in which the rate constant for the decomposition reaction is of the order 10 to 10 min.-1 Table IIUI>-1M shows the results. The decomposition temperature decreases in the order alkyl and aryl azides > azidofor-mates and sulfonyl azides > acyl azides. The difference in reactivity between acid azides and alkyl or aryl azides can be explained easily in terms of resonance stabilization in the azide... 

Kwart and Kahn have found that benzenesulfonyl azide forms a complex with freshly reduced copper powder.189 190 This copper azide complex decomposes at a lower temperature than the pure sulfonyl azide. In refluxing methanol, benzene-sulfonamide (27) is isolated as the major product. In the presence of dimethyl sulfoxide, N-benzenesulfonyldimethyl-sulfoximine (28) is obtained in almost quantitative yield. In cyclohexene solution benzenesulfonamide (29), N-benzenesul-fonyl-7-azabicyclo[4.1.0]heptane (30), and 1-cyclohexenylben-zenesulfonamide (31) are isolated as the main reaction products. According to the authors, Schemes VII and VIII represent an acceptable interpretation of the experimental data.189 190 In pure alcohol, the decomposition should occur by two competitive reactions (Scheme VII) producing benzenesulfonamide together with a ketone and oxidized copper. These last two products have indeed been observed in the reaction mixture. In the presence of DMSO, it seems that a copper-nitrene intermediate is formed which is trapped by DMSO. In cyclohexene solution, the authors have observed that the aziridine (30) disappears from the product composition when DMSO is added. The yield of enamine 31, however, is... 

Sulfonyl azides react with olefins at a temperature which is much lower than the decomposition temperature of the azides (120-150°). The isolated products are aziridines and anils. The addition can be conceived as a result of two consecutive reactions, namely a 1,3-dipolar cycloaddition of the azide to the olefin immediately followed by decomposition of the formed unstable triazoline. As no triazolines can be detected, these reactions can also be regarded as a concerted addition with concomitant loss of nitrogen. 

Sulfonyl azides react rapidly (at room temperature) with enamines, and here, too, no triazolines are isolated. The reaction products nevertheless can be easily explained when an intermediate triazoline is postulated. The hypothetic triazoline can then decompose in three different ways leading either to amidines and nitrogen, or to amidines and diazoketones, or to triazoles and sulfonamines.226-241-270-272 A typical example of each mode of decomposition is given in Scheme IX. 

The reactions of vinyl ethers with sulfonyl azides have been described by several authors.260-273-275 From dihydropyran the arylsulfonimines of 5-valerolactone (87) are obtained. These compounds rearrange at ca. 180° into N-arylsulfonyl-2-piperidones (88) (Chapman rearrangement).276... 

The reaction of azides with ethoxyacetylene (98) has been studied by Italian authors. With aliphatic and aromatic azides, the expected 1-substituted 5-ethoxy-l,2,3-triazoles (99) are obtained.310-311 Sulfonyl azides, on the other hand, react with ethoxyacetylene at room temperature to yield no triazoles but the valence tautomeric diazo compounds (100).312-313... 

With a range of methods available for the formation of 1,3-dicarbonyl compounds, the dicarbonyl diazomethanes can be readily prepared via a simple diazo transfer reaction with sulfonyl azide. This has made a vast array of dicarbonyl diazomethanes available, which enhances the versatility in organic synthesis. A selection of examples from recent literature to illustrate the versatility of the cyclopropanation using dicarbonyl diazomethane in the construction of natural products as well as other biologically active compounds is described below. 

The diazo transfer reaction with sulfonyl azides has been extensively used for the preparation of diazo compounds with two electron-withdrawing groups (equation 1 ).28 Toluenesulfonyl azide (13a)29 is the standard reagent used, but due to problems of safety and ease of product separation, several alternative reagents have been developed recently. n-DodecylbenzenesuIfonyl azide (13b)30 is very effective for the preparation of crystalline diazo compounds, while p-acetamidobenzenesulfonyl azide (13c)31 or naph-thalenesulfonyl azide (13d)30 are particularly useful with fairly nonpolar compounds. Other useful reagents are methanesulfonyl azide (13e)32 and p-carboxybenzenesulfonyl azide (13f).33... 

The reaction of dienamines and sulfonyl azides provides a method for the synthesis of vinyldiazomethanes.233,431 Likewise, the pyrolysis of a fluo-rinated 1-benzyltriazoline over a nickel surface yields difluorodiazometh-ane.145 The formation of diazo compounds from the reaction of azides with alkylidene phosphoranes apparently originates from an intermediate triazoline compound (Scheme 145)408,411 412,415,441... 

Aminoamidines (105) are also formed from the reaction of picryl and sulfonyl azides with indoles (103) when R1, R2, and R3 are all alkyl groups or a... 

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