Sulphonyl migration

Sulphonyl a-hydrogens, acidity of 402-405 Sulphonylisoxazolines, reactions of 791 Sulphonylmercuration 172 Sulphonylmethanes, acidities of 592 Sulphonyl migration 169 Sulphonyl nitrenes 810 2-Sulphonyloxaziridines 72 Sulphonyloxiranes 169 synthesis of 639... 

An alkyl-group migration has been observed in some 7V-sulphonyl-phosphazenes ... 

C-10, presumably via a path involving the intervention of a C-10 carbonium ion, elimination, and reprotonation. An unusual fragmentation of ring A has been observed47 in the treatment of 6a-hydroxy-7-oxoabieta-8,ll,13-triene (43) with toluene-p-sulphonyl chloride. The formation of the /3-naphthol (46) may proceed via the enol (44), followed by a methyl migration to (45) and then fragmentation. 

SCHEME 11. Radical chain mechanism for the [l,3]-sulphonyl group migration in N-vinylsulphonamides... 

The migration of methyl to sulphur observed in reactions of o-mercapto-benzoic acid methyl ester with primary aliphatic amines, possibly via an S i mechanism, contributes another example to an extensive list of interactions of aromatic or/Ao-substituents. More conventional nucleophilic substitution processes include syntheses of L-selenomethionine, MeSeCH2 -CHa CH(NH2) C02H, and its c-ethyl and S e-benzyl analogues by treatment of O-toIuene-p-sulphonyl-L-homoserine with appropriate organo-selenium nucleophiles also, analogous reactions of hydroxy-acid... 

Details have appeared on the behaviour of methyl 2,3-0-isopropylidene-4-0-toluene-p-sulphonyl-a-D-lyxo- and -P-L-ribo-pyranoside towards nucleophiles (see Vol. 8, p. 53). The dithiepane derivatives (127) and (128) were formed via the intermediate (126), resulting from sulphur migration, when the mesylate (125) was treated with sodium azide in warm DMF ° (see also Chapter 15). The reactions of... 

Four-membered Ring Nitrogen Heterocycles.— The synthesis of azetidine and its derivatives by akylation of an external or an internal amine is well known, and two more examples were reported in 1980. Interest in simple alkyl substituted azetidines now lies in studies on their stereo-preferences, and conversions to other important systems. That said, two photochemical investigations surprisingly turned up such systems as unexpected major products. Pete et while extending their work on 2-amino-cyclohex-2-enones examined the consequence of N-sulphonylation on their photochemical behaviour, and instead of getting aziridines as the principal products, they obtained azetidines (Scheme 35). These reactions were not as clean as the earlier ones, and aryl migration... 

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