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Scheme 18. Three-step, one-pot preparation of arylethers: products are formed because the reagents are polymer-supported.

Ley et al. described a combination of an oxidant, polymer-supported perruthenate 62, and of a reducing agent, polymer-supported cyano borohydride 96. Readily available alcohols 65 as a primary feedstock were oxidized to intermediate 66 and further reacted with amines to afford higher substituted amines, e.g., 97 (Scheme 19) [77]. These were further sulfonylated using polymer-supported sulfonylpyridinium ion 98 to give sulfonamides 99 [77].

A variety of other sequential, clean, multistep transformations solely based on PSRs have been described. Starting from alcohols 65, which were oxidized to the corresponding car-bonyl compounds (66), a,P-unsaturated ketones 100 were prepared in a Mukaiyama aldol condensation using Nafion-TMS 101 as silylating agent and Lewis acid [78]. The resulting enones were treated with hydrazines 102 to give clean final products, 4,5-dihydro-1H-pyra-zoles 103 [78],

NaCNBH,

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