From acyl sulfonamides

Methyl pyrazine-2-carboxylic acid is refluxed with thionyl chloride in anhydrous benzene for approximately 12 hours. Benzene and thionyl chloride excess is removed by distillation. Then some anhydrous dioxane is added and this acid chloride solution is allowed to drop into p-(/3-aminoethyl)-benzenesulfonamide suspension in dioxane and anhydrous pyridine. The resulting mixture is then refluxed for 3 hours. Dioxane is removed by distillation and then the residue is washed with water and acetic acid. The raw acylated sulfonamide is then filtered and crystallized from 95% ethanol, thus obtaining a product of MP 200 to 203 C. 

Particularly, some newly developed drags, which incorporate the N-acyl sulfonamide moiety [8-10], are synthesized from the parent sulfonamides, by their coupling with acid chlorides or carboxylic anhydrides in basic conditions [11-15]. Unfortunately all these methods lead to substantial waste products. Less common reports mentioning this transformation under acidic conditions (Bronsted or Lewis acids) do not systematically examine the purpose and limitations of the reaction [16]. 

This compound is derived from acylation of the sulfonamide moiety of valdecoxib, followed by treatment with sodium hydroxide. The acidic acylsulfonamide forms a water-soluble sodium salt that is stable for administration but cleanly delivQS valedecoxib once in plasma. 

Symmetrical A-sulfonyl sulfonamides, i.e., sulfonimides, can be prepared from the amine and two equivalents of sulfonyl chloride and base. The unsym-metrical A/-sulfonyl sulfonamides and the related A-acyl sulfonamides can be obtained by the reaction of a sulfonamide or carboxamide with an acid halide. 

The N-acyl sulfonamide is highly stable under acidic and basic conditions. This stability is lost when it is JyT-alkylated. In these conditions, the C-terminal acyl functionality of the peptide chain becomes more susceptible to nucleophilic attack, allowing its release from the solid support. Thus, the cleavage is performed in two steps the alkylation of the resin and the nucleophilic attack of the peptide at the C-terminal position. The most used alkylating agent is iodoacetonitrile, while different nucleophilic agents can be used to afford different functionalities at the C-terminus (amide, thioesters). 

Until now, the most efficient approach to synthesize Freidinger lactams 147 started from a resin-bound cinnamylamine 144. A Fukuyama-Mitsunobu reaction to 145 followed by sulfonamide cleavage and a consecutive appropriate acylation built up the diene 146, which underwent ring-closing metathesis involving Grubb s catalyst 123 to generate the desired lactams 147 (Scheme 27, Table 5) [35d]. 

Carbenes from Diazo Compounds. Decomposition of diazo compounds to form carbenes is a quite general reaction that is applicable to diazomethane and other diazoalkanes, diazoalkenes, and diazo compounds with aryl and acyl substituents. The main restrictions on this method are the limitations on synthesis and limited stability of the diazo compounds. The smaller diazoalkanes are toxic and potentially explosive, and they are usually prepared immediately before use. The most general synthetic routes involve base-catalyzed decomposition of V-nitroso derivatives of amides, ureas, or sulfonamides, as illustrated by several reactions used for the preparation of diazomethane. 

For a general, simple high yield indole synthesis from anilines and methylthioacetaldehyde etc. see JACS 95,588,591,2718,6508 (1973). For indoles from N-( /3 -hydroxy-ethyl aniline esters see BSC 2485(1973). For a 2-acyl-indoles in one step from orthoamino-ketones and alpha-haloketones or 2-carboxyindoles from sulfonamides of ortho-aminocarbonyls see JOC 38,3622-24(1972). Indole and 5-Br-indole in 4 steps from beta-naphthol see Chem. Het. Cpds. (Russ.) 753(1973). Indole-JOC 37,3622(1972). 

Miller s biomimetic approach inspired Ishihara [234] to develop a minimal artificial acylase for the KR of mono-protected cw-l,2-diols and A-acylated 1,2-amino alcohols. Derived from (S)-histidine, Ishihara s organocatalyst contains only one stereogenic centre and incorporates a sulfonamide linkage in place of a polypeptide chain to allow the NH group to engage as an H-bond donor with the substrates (Fig. 13) [234]. 

Several different types of linker have been developed that yield amides upon cleavage. These linkers can often also be used to prepare sulfonamides, carbamates, or ureas. There are essentially three different strategies for the release of amides from insoluble supports (a) cleavage of the benzylic C-N bond of resin-bound N-alkyl-N-benzylamides (backbone amide linkers, BAL linkers), (b) nucleophilic cleavage of resin-bound acylating agents with amines, and (c) acylation/debenzylation of resin-bound /V-benzyl-/V,A -dialkylamines. 

Sulfonamides prepared from 9-(chlorosulfonyl)anthracene and polystyrene-bound primary amines can be converted into amides by N-acylation of the sulfonamide (carboxylic acid anhydride, DMAP, pyridine, THF, 24 h) followed by nucleophilic desulfo-nylation with neat 1,3-propanedithiol/DIPEA [213] (Entry 4, Table 10.13). An example of the use of sulfonamides as linkers for amines is given in Table 3.23. 

Diazepanones have been prepared on insoluble supports by intramolecular nucleophilic cleavage, by intramolecular Mitsunobu reaction of sulfonamides with alcohols, and by intramolecular acylations (Table 15.36). As in the case of azepines, these reactions do not always proceed smoothly, and care must be taken to prevent potential side reactions from occurring. For instance, intramolecular acylations in peptides containing aspartic acid (Entry 2, Table 15.36) will generally lead to the formation of suc-cinimides (see Table 13.20) unless A-alkylamino acids are used. 

A-Alkyl-,61 AT-acyl-,62,63 and AT-sulfonyl-l,2-benzisothiazolinones64 are readily obtained from the parent compound [(53) R = H] by treatment with alkylating, acylating, or sulfonylating agents or, in the case of A-acyl and A-sulfonyl derivatives, by using an amide or sulfonamide, instead of a primary amine, in the reaction above... 

---