Transfers phenylsulfonyl groups

Lithiated indoles can be alkylated with primary or allylic halides and they react with aldehydes and ketones by addition to give hydroxyalkyl derivatives. Table 10.1 gives some examples of such reactions. Entry 13 is an example of a reaction with ethylene oxide which introduces a 2-(2-hydroxyethyl) substituent. Entries 14 and 15 illustrate cases of addition to aromatic ketones in which dehydration occurs during the course of the reaction. It is likely that this process occurs through intramolecular transfer of the phenylsulfonyl group. 

With a phenylsulfonyl group as X (Scheme 41) the intermediate, after rearrangement, will decompose directly to an aldehyde function, which reacts wiA excess alkyllithium to form an unsaturated alcohol. The often efficient transfer of chirality from C-1 of an optically active allylic alcohol to the newly created stereogenic centers at C-3 and/or C-4 is another valuable aspect of the 2,3-Wittig rearrangement which has already found extensive use in natural product synthesis. ... 

Progress continues to be made in the area of novel asymmetric methods. For example, the [l,4]diazepanone 16 has been shown to promote asymmetric epoxidation with modest enantioselectivities in the presence of Oxone and a mild base. The active oxygen transfer species is believed to be the chiral dioxiranc 17, which adopts a twisted conformation and imposes a facial bias via the phenylsulfonyl groups. Yields are relatively low (< 50%), presumably due to Baeyer-Villiger degradation of the chiral auxiliary (16 18). This... 

Several methods for synthesizing IV-protected (usually with electron-withdrawing groups) 2-and 3-haloindoles have been developed and the resulting haloindoles are much less prone to decomposition than the unsubstituted compounds. Bromination of A/-(phenylsulfonyl)indole (3), which is readily available via lithiation [9, 10] or phase-transfer chemistry [11, 12], affords 3-bromo-l-(phenylsulfonyl)indole (4) in nearly quantitative yield [12],... 

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