Arylsulfonyl derivatives

When 4-hydroxybenzoic acid was used in place of phenol, most of the 4-hydro-xybenzoic acid derivatives crystallised out on addition of the crude reaction mixture to water, the remainder being removed by base extraction of the filtrate. 

The fine tuning of reduction potential was useful for optimising the cleavage of arenesulfonamides by electrolysis in acetonitrile using a mercury pool cathode and platinum anode, with phenol as the proton source and 0.1 M tetraethyl-ammonium bromide as anolyte.  

For the remainder of this section, we will briefly survey a few of the less common arylsulfonyl protecting groups beginning with the yV-9-anthrylsulfonyl group. A synthesis of the hexahydropyrrolo[2,3-f Jindole segment of the Hi-mastatins featured the use of a 9-anthrylsulfonyl group to protect and activate 

1 was first treated with A bromosuccinimide to create a pyrroloindole ring 

2- and 4-Nitrophenylsulfonyl (Ns) groups have two assets. Firstly, they are stable towards acid and base but are cleaved under mild and specific conditions with thiols and a weak base such as potassium carbonate or DIPEA. Secondly, the nitro substituent enhances the acidity of the sulfonamide proton thereby 

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Lactols and their acetals can be transformed easily into their 2-arylsulfonyl derivatives 337 by reaction with a sulfinic acid under Lewis acid activation. The corresponding organolithiums are prepared by deprotonation with n-BuLi or LDA and, after reaction with electrophiles, a /(-elimination of sulfinic acid afforded a cyclic a-substituted enol ether514,547,548. 2-Lithio-2-(arylsulfonyl)tetrahydropyrans equilibrated to give mainly the anomer with the lithium atom at the equatorial position549. 

Aromatic and heterocyclic aldehydes have been prepared from hydra-zides, via the arylsulfonyl derivative, in 50-65% and 20-40% yields, respectively the method fails in the aliphatic series. The hydrazide is treated with benzenesulfonyl chloride in pyridine, and the subsequent product is isolated by precipitation with water and decomf>osed by heating with sodium carbonate in ethylene glycol or glycerol at 160°. 

Although (1) has not been used in solid-phase oligonucleotide synthesis, another more stable arylsulfonyl derivative, l-(mesityl-sulfonyl)-3-nitro-l,2,4-triazole (MSNT), is commonly used in that strategy by the phosphotriester approach. ... 

On the other hand, the introduction of a phenoxy group at the hydroxyl function of A -arylsulfonyl derivatives of trani-4-hydroxy-L-proline resulted in more hydrophobic catalysts, which could be used to promote aldolisations of cyclic ketones with aromatic aldehydes in water with excellent yields, diastereo-and enantioselectivities, as shown in Scheme 2.21. ... 

The accelerative effect of London forces of attraction between a nucleophile and nearby substituents has been investigated in quinoline and benzene derivatives by Bunnett and co-workers, ii7b, 307 In 2-, 4-, and 6-arylsulfonyl-3-nitrochlorobenzene, Loudon and Shulman found that arylmercaptide ion, presumably through this effect, displaced the arylsulfonyl group while methoxide or ammonia displaced the nitro or chloro group. 

If the rotational freedom of the aryloxy group is restricted, as in 4-[(arylsulfonyl)methyl]-2H-l-benzopyranes (55), the remote group interaction is not possible anymore and these derivatives fragment mainly by ejecting ArS02H and S0238 (equation 26). 

Note When attached to an atom other than carbon, alkyl- or arylsulfonyl groups are usually known as alkane- or arenesulfonyl groups (lUPAC Rule C 21)1076 considerd as acyl-type derivatives rather than sulfones. 

Polar C=Y double bonds (Y = NR, O, S) with electrophilic carbon have been added to suifinic acids under formation of sulfones. As in the preceding section one must distinguish between carbonyl groups and their derivatives on the one hand, and carboxylic acids (possessing leaving groups at the electrophilic carbon) on the other. Aldehydes " of sufficient reactivity—especially mono-substituted glyoxals - —and their aryl or arylsulfonyl imines have been added to suifinic acids (in a reversible equilibrium) to yield a-hydroxy or a-amino sulfones the latter could also be obtained from the former in the presence of primary amines (equation 26). 

The derivatives bearing the arylsulfonyl groups at the 3- position of the ring proved to be more potent than the 4-arylsulfonyl substituted isomers, and the pair of isomeric phenyl-phenylsulfonylfuroxans (43a,b R=Q,I13) was more potent than the cor-... 

Tab. 10.6 summarizes the application of this transformation to a variety of racemic secondary allylic carbonates using the lithium anion of 4-methoxy-N-(p-toluidine)-benzene sulfonamide. The excellent regioselectivity obtained for this type of substitution provided an important advance in the synthesis of N-(arylsulfonyl)anihnes using the metal-catalyzed allyhc amination reaction. The allyhc alcohol derivatives examined... 

The combination of allylic amination, ring-closing metathesis, and a free radical cyclization provides a convenient approach to the dihydrobenzo[b]indoline skeleton, as illustrated in Scheme 10.10. The rhodium-catalyzed aUylic amination of 43 with the lithium anion of 2-iodo-(N-4-methoxybenzenesulfonyl)arrihne furnished the corresponding N-(arylsulfonyl)aniline 44. The diene 44 was then subjected to ring-closing metathesis and subsequently treated with tris(trimethylsilyl)silane and triethylborane to afford the dihydrobenzojhjindole derivative 46a in 85% yield [14, 43]. 

Dichloro-bis-dithiolium salt 85 obtained from M-ethyldiisopropylamine, S2CI2 and DABCO in chloroform at room temperature reacted with arenesulfonamides and their Af,N-dichloro derivatives with the formation of Ahhf -bis(arylsulfonyl)-dithiolothiazine diimines 90 in modest yields (2001JCS(P1)2409 Scheme 42). 

In 2004, Rossello and colleagues synthesized some matrix A-arylsulfonyl-substituted alkoxyaminoacetohydroxamic acid derivatives designed as oxa-analogues of known sulfonamide-based metalloproteinases. 

Since benzenesulfonyl peroxide was used as an initiator in polymerization reactions, it was thought that a free radical aromatic substitution of benzene by the benzenesulfonoxy radical takes place. A detailed study by Dannley and Knipple reveals that attachment of the sulfonoxy group derived from a bis(arylsulfonyl) peroxide to the aromatic ring occurs by electrophilic aromatic substitution (equation 5) °. 

Hoffman and coworkers have extensively studied the reactions between amines and sulfonyl peroxides. When primary amines reacted with arylsulfonyl peroxides at —78 °C in ethyl acetate, A-alkyl-O-arylsulfonyl hydroxylamine derivatives were obtained (equation 8), whereas when various primary and secondary amines reacted with sulfonyl peroxides, oxidative deamination was observed. ... 

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