Oxidative coupling copper trifluoromethanesulfonate

While a-sulfonyl lithiated carbanions are oxidatively coupled with copper(II) trifluoromethanesulfonate (eq 2), Cu(OAc)2 oxidizes them to the corresponding ( )-Q ,/3-unsaturated sulfones (eq 3).13... 

Even if no substituents were present at the porphyrin ()-positions, neither meso- nor P P couplings were observed. Nevertheless, a good choice of oxidant also allowed the synthesis of directiy fused diporphyrins. Indeed, meso-meso, (T-P and meso-% meso- doubly linked and P P, meso-meso, P P triply linked dimers were synthesized by oxidation with tris(4-bromophenyl)aminium hexachloroantimonate (BAHA), AuCl3-AgOTf combination (Tf = trifluoromethanesulfonate), phenylio-dine bis(trifluoroacetate) (PIFA) or copper (II) perchlorate or tetralluoroborate (Fig. 21a-c) [157-161]. 

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