Azidation with sulfonyl azides

The chemistry of nitrogen electrophiles R R2NX (I) was excellently summarized in 1989Ia. Recent studies in the field of stereoselective electrophilic amination, however, have shown that azidation with sulfonyl azides III, reactions with di-tert-butyl azodicarboxylate (II) and reactions with 1-chloro-l-nitroso reagents IV, are superior to the previously mentioned nitrogen electrophiles. 

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... 

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. 

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... 

Diazocarbonyl compounds can be prepared on insoluble supports by diazo group transfer with sulfonyl azides or by diazotization of primary amines. Diazo group transfer from sulfonyl azides to 1,3-dicarbonyl compounds proceeds on cross-linked polystyrene as smoothly as in solution (Table 10.19). When 3-keto esters or amides are... 

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... 

N-Methylindole acts like an enamine with sulfonyl azides and gives a diazoimino compound.443-445 So does dihydropyridine but only in the presence of 5% lithium hydroxide (Scheme 147).242 A triazole is postulated to be formed from the triazoline followed by a ring opening oxidation of diazoamino compounds to triazoles has been known to proceed via a diazoimino compound in equilibrium with the triazole (Scheme 1 19).285-3"-400... 

Scheme 2 Preparation and examples of aryl azides, (a) Three possible routes for the conversion of an aryl amine into its aryl azide (i) via diazotization [44], (ii) by the use of triflyl azide [45], and (iii) with sulfonyl azides 15 (R = imidazole [46] or R = benzotriazole [55]). (b) Examples of substituted aryl azides...

Triorganoantimony and -bismuth react with chloramine-T or with sulfonyl azides to give the corresponding imines (equations 250 - and 251 ). 

Based upon their previous studies with DEAD prompted dehydrogenation of tertiary amines and tandem reaction with sulfonyl azides, [37] Li believed that DEAD would provide the desired iminium ion intermediate 32 without the need for an aryl substituent (Scheme 19). 

C. Ollivier and P. Renaud, A novel approach for the formation of carbo-nitrogen bonds Azidation of alkyl radicals with sulfonyl azides, J. Am. Chem. Soc., 123 (2001) 4717-4727. 

Scheme 10.8 (a) Products of CuAAC reactions with sulfonyl azides, (b) Possible pathways leading to ketenimine intermediates. 

Proline catalysis was further extended to the a-sulfamidation of a,a-branched aldehydes (Scheme 5.34). The reaction of hydratropaldehyde with sulfonyl azides yields the sulfamidated products, such as 35 in moderate yields and selectivities. 

Scheme 29 A Reaction of alkyl azides 130 with aryl isocyanates 131 to yield 1-alkyl-4-aryl-A -tetrazoline-5-ones 132 B Reaction of alkyl azides 133 with acyl isocyanates or carboalkoxy isocyanates 134 to l-alkyl-4-acyl-A -tetrazoline-5-ones and l-alkyl-4-carboalkoxy-A -tetrazoline-5-ones 135 (C). Reaction of aryl azides and alkyl azides 137 with sulfonyl isocyanates 138 to produce l-aryl-4-sulfonyl-A -tetrazoline-5-ones and l-alkyl-4-sulfonyl-A -tetrazoline-5-ones 139 [107]...

The two principal and most general synthetic routes to a-diazocarbonyl conpounds are (1) acylation of diazoalkanes and (2) diazo-transfer reactions to carbonyl conpounds with sulfonyl azide reagents. Caution Diazo conpounds and azide reagents are presumed to be toxic and potentially explosive, and appropriate safety measures should be deployed when handling these conpounds. 

Rhodium-Catalyzed Intermolecular Amidation of Arenes with Sulfonyl Azides... 

A facile access to A-sulfonylimidates and their synthetic utility for the transformation to amidines and amides, (b) E. J. Yoo, S. H. Park, S. H. Lee, S. Chang, Org. Lett. 2009, 11, 1155-1158. A new entry of copper-catalyzed four-component reaction facile access to a-aryl P-hydroxy imidates. (c) R. Husmann, Y. S. Na, C. Bohn, S. Chang, Chem. Commun. 2010, 46, 5494—5496. Copper-catalyzed one-pot synthesis of a-functionalized imidates. (d) W. Song, W. Lu, J. Wang, P. Lu, Y. Wang, J. Org. Chem. 2010, 75, 3481-3483. A facile route to y-nitro imidates via four-component reaction of alkynes with sulfonyl azides, alcohols, and nitroolefins. (e) G. Murugavel, T. Punniyamurthy, Org. Lett. 2013, 15, 3828—3831. Novel copper-catalyzed multicomponent cascade synthesis of iminocoumarin aryl methyl ethers. 

S. Li, Y. Luo, J. Wu, Org. Lett. 2011, 13, 4312 315. Three-component reaction of N -(2-alkynylbenzylidene)hydrazide, alkyne, with sulfonyl azide via a multicatalytic process a novel and concise approach to 2-amino-H-pyrazolo[5,l-a] isoquinolines. 

In 2012, Kim etal. [85] reported the intermolecular amidation of arenes with sulfonyl azides, which is a direct C-H process (Scheme 4.22). A cationic Rh complex was used in air. The application was showcased by the synthesis of 6-arylpurine derivatives, which show antimycobacterial, cytostatic, and anti-HIV activity. The reaction scope was successfully demonstrated. 

A study of reactions of benzocyclic jS-keto esters with sulfonyl azides has provided further indication, from results for a benzosuberone, that the electronic features of the azide can profoundly influence the distribution of azidation, diazo transfer, and ring contraction products. 

The reaction of alkyl azides with sulfonyl isothiocyanates at room temperature affords the [3-1-2] cycloadducts 90 in 50-75 % yields... 

Azides can undergo cycloaddition reactions with sulfonyl isocyanates as well. L Abbe et al. showed the formation of 4-sulfonyl-tetrazolin-5-ones that underwent thermolylically-induced decomposition and produced carbodiimides with the formation ofNa. ... 

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