Azasulphonium Ylides

Azasulphonium Ylides.—A valuable series of papers has appeared on the azasulphonium route to or/Ao-alkylated aromatic amines, indoles, and oxindoles. This procedure involves (i) generation of an azasulphonium salt such as (27), 

Vilsmaier has reported that succinimido-sulphonium salts may undergo [1,2]- and [2,3]-sigmatropic rearrangement, giving JV-methylthiomethyl succinimide and the appropriate methylthiomethyl ether, respectively. 

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Azasulphonium Ylides.—Azasulphonium ylides, which are intermediates in the rearrangements of A-aryl-azasulphonium salts in the orrAo-functionalization of aromatic amines, can be isolated as stable compounds if suitable substituents are incorporated. ... 

Azasulphonium ylides have been extensively studied (see Vol. 5, pp. 81-2 and 111) because of their well-known synthetic utility for exclusive ortho-functionalization of aromatic amines or phenols. By this process, various functionalized anilines (48) and phenols (49) have been synthesized. 

Alkylation of amines has received attention from several groups. Some 2-(l-thiophenoxybutyl)-acetanilides (160) have been obtained by [2,3]-sigmatropic rearrangement of azasulphonium ylides (161), formed from the sulphimine (162) by reaction with acetic anhydride (Scheme 24). 

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