O

(SJ-zearalenone 97

Suzuki Coupling

Suzuki coupling after a cleavage reaction is potentially applicable in a multifunctional sense. Because of the tendency of the boronic acid derivative to give homo-coupling products, the need to use additional ligands, and the low volatility of the boronic acid derivative, however, more or less tedious work-up is required after these types of transformation. A few studies have proven that some functionality, when generated during cleavage, can act as the leaving groups for a subsequent Suzuki reaction.

Arylmethyl(homobenzyl)ethylsulfonium salts are appropriate substrates for Suzuki-type coupling reactions. In this reaction, performed on a polymer-bound sulfonium tetrafluoroborate, the benzyl fragment on the sulfur atom was transferred to the boronic acid residue. The sulfonium salt was prepared from an al-kylthiol resin by alkylation with a substituted benzyl halide to give thioether 98 and subsequent alkylation with triethyloxonium tetrafluoroborate. Reaction with a boronic acid derivative yielded diaryl methanes 99 [94] (Scheme 6.1.22).

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