Alkyl tosylates, Suzuki cross-coupling

This route involves the conversion of a 3,4-diiodopyrrole (139) to the corresponding 3,4-diboronate ester (140) followed by a bis Suzuki cross-coupling reaction with a bromoquinoline, which generates the halitulin core (141). This pyrrole (141) is then alkylated with a tosylated cycloazadecane to generate a pentasubstituted pyrrole (143), which is converted to halitulin by debenzylation under hydrogenolysis conditions. 

Alkyl-Alkyl Suzuki Cross-coupling of Functionalized Alkyl Boranes with Alkyl Bromides, Chlorides and Tosylates... 

Scheme 3.85 Alkyl-alkyl Suzuki cross-coupling of functionalized alkylboranes with functionalized alkyl bromides, chlorides and tosylates.

Unfortunately, attempts to extend the use of Pd/PCy3 to Suzuki reactions of alkyl tosylates were unsuccessful. However, by modifying the conditions, it was possible to develop a catalyst system that is effective for cross-couplings of a range of primary tosylates (Eq. 4) [16]. Scheme 1 illustrates the remarkable sensitivity of the coupling reaction to the structure of the trialkylphosphine... 

The 2,N-diallylarenes 35 are obtained (i) from 2-iodo-N-alkyl- (or acyl-) anilines 34 by Suzuki-Miyaura cross-coupling and subsequent N-allylation and (ii) from N-diallylanilines 37 by sequential Lawis-add induced aza-CiAisEN rearrangement and N-tosylation [27]. 

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