Sulphonamides rearrangement

Sulphonamides, mass spectra of 157, 158 Sulphonanilide-anilinosulphone rearrangement 170, 171 Sulphonates - see also Thiosulphonates arylsulphonylmethyl - see... 

Knipe et al. (1976) reported that N-(2-hydroxyethyl)-p-nitrobenzene-sulphonamides 11581 undergo a desulphonative double Smiles rearrangement in aqueous alkali (28) to produce the aniline derivative [160). Upon replacing... 

Orthophosphoric and benzylphosphonic acids have been selectively alkylated with triethyl phosphite in a new synthesis of mono-, di-, and triethyl phosphates and of mono- and di-methyl phosphonates.62 A-Methylol carboxamides and sulphonamides react with trialkyl phosphites to give the phosphonate derivatives (78) and (80), respectively.63 However, the mechanism appears to be quite different in each case while the carboamides react by a transesterification-rearrange-ment pathway, the sulphonamides undergo elimination-addition via the imine (79). 

A-Aryl sulphonamides have not been investigated in detail, but anion translocation from the S -substituted ring to the A-substituted ring takes place in diaryl sulphonamides 118, ultimately leading to the rearrangement shown in Scheme 51 . ... 

Decomposition of sulphonyl a zides in aromatic solvents may lead to aromatic substitution , which is thought to involve the addition of the singlet nitrene to the aromatic nucleus, followed by further rearrangement to give productsIn aromatic solvents, the yields of unsubstituted sulphonamides (hydrogen abstraction) are better than in aliphatic hydrocarbons Due to the absence of biaryls in... 

The lability of the substituent in I-ethoxyisochroman (116) towards nucleophiles continues to be studied with benzylamine, ( )-l-benzylamino-isochroman (117) was formed, but, when this was heated at a higher temperature, it rearranged into 4-benzylisoquinoline (118) via the ring-opened intermediates. Replacing the amine by an arylamine gave the 1-aminoisochroman (119 R = NHAr) or l-(4-aminoaryl)isochroman (119 R = 4-NH2C6H4), or a mixture of both. Reactions with amides and sulphonamides have also been studied. ... 

Rearrangements of sulphonic acids and their derivatives are many and varied. Surprisingly, though a few reviews exist for sulphonic acids and sulphonamides, this general class of compounds has not been reviewed extensively, particularly as a coherent set. This... 

Lossen-type rearrangement of an O-sulphonate ester of N-hydroxybenzene-sulphonamide (equation 26) is also known75. The intermediate sulphonylamine can be trapped by solvent methanol or by added aniline. 

The rearrangement of an Af-arylsulphonamide, or an JV-arylsulphamide, to the isomeric aminoaryl sulphonyl compound (equation 43) is now a well-known reaction. The reaction is the nitrogen analogue of the Fries rearrangement (Section III.A.). For sulphonamides, acid-catalysed, base-catalysed, thermally promoted and photochemically promoted rearrangements have been observed for sulphamides, only the thermal and base-catalysed processes have been reported. 

SCHEME 7. Mechanism of the sulphonamide—aminosulphone rearrangement (after Closson114)... 

It has been noted that all these rearrangements, including acyclic sulphonamides, proceed more efficiently in the presence of two equivalents of base, i.e. under conditions favouring the second metalation117. 

SCHEME 8. Mechanism of the base-catalysed sulphonamide-aminosulphone rearrangement (after Hellwinkel)... 

SCHEME 9. Sulphonamide-aminosulphone rearrangement via halogen-metal exchange... 

The reaction involves the oxyanion of the alcohol which then undergoes an SNAr attack at the ipso sulphonyl carbon atom of the activated aryl ring. The SNAr process is faster for secondary sulphonamides, than for tertiary ones, i.e., R = H Et > Me Ph. This is attributed to formation of the sulphonamide anion and that this anion adopts a preferred conformation conducive to the S Ar reaction127. Alkyl substituents in the hydroxy alkyl group also increase the rate of the rearrangement reaction127. 

N-Aryl A-benzoyloxysulphonamides (102) rearrange on heating to the corresponding A-(2-benzoyloxyaryl) sulphonamides (103) (equation 74)159. Unlike the iV-sulphinyl-... 

Sulphonamides are weakly nucleophilic species and react only with the more reactive electrophiles e.g. MeS03F154. However, participation of the sulphonamide nitrogen atom in the rearrangement of bicyclic N-sulphonyl amines has been occasionally repor-... 

N-[(/-Butylsulphinyl)oxy] sulphonamides (59) rearrange with N—O cleavage via sulphonamidyl radicals 60 to give 61 in ca 20% yield in a radical cage recombination process, along with products formed after escape from the cage (equation 36)162. 

Hexamethylphosphoramide has found important uses as a solvent in various organic reactions, such as carboxylic ester formation, hydrolysis of sulphonamides, alkylation of ketones, decyanation of nitriles, the Beckmann rearrangement and so on. HMPA may be used to make cyclodiphospha-zanes (7.250). 

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