Pyridine sulfinates are stable and straightforward to prepare nucleophilic coupling partners for palladium catalyzed cross-coupling reactions with aryl and heteroaryl halides. The scope with respect to the halides coupling partner is considerable, and allows the preparation of a broad range of linked pyridines.

Heterocyclic sulfinates are effective reagents in palladium-catalyzed coupling reactions with aryl and heteroaryl halides, often providing high yields of the targeted biaryl. However, the preparation and purification of complex heterocylic sulfinates can be problematic. In addition, sulfinate functionality is not tolerant of the majority of synthetic transformations, making these reagents unsuitable for multistep elaboration. Herein, we show that heterocyclic allylsulfones can function as latent sulfinate reagents and, when treated with a Pd(0) catalyst and an aryl halide, undergo deallylation, followed by efficient desulfinylative cross-coupling. A broad range of allyl heteroarylsulfones are conveniently prepared, using several complementary routes, and are shown to be effective coupling partners with a variety of aryl and heteroaryl halides. We demonstrate that the allylsulfone functional group can tolerate a range of standard synthetic transformations, including orthogonal C- and N-coupling reactions, allowing multistep elaboration. The allylsulfones are successfully coupled with a variety of medicinally relevant substrates, demonstrating their applicability in demanding cross-coupling transformations. In addition, pharmaceutical agents crizotinib and etoricoxib were prepared using allyl heteroaryl sulfone coupling partners, further demonstrating the utility of these new reagents.

Enantiomerically enriched [3.1.0] bicycles containing vicinal quaternary centers were synthesized from [1,6]-enynes using a cyclopentadienylruthenium catalyst containing a tethered chiral sulfoxide. The reaction was complicated by the fact that the substrates contained a racemic propargyl alcohol that could affect the selectivity of the process. Nonetheless, high levels of enantioinduction were observed, despite complications arising from the use of racemic substrates. Mechanistic studies showed that while the utilization of either enantiomer of the propargyl alcohol led to high product enantiomeric ratios when the reaction was conducted in acetone, a significant matched/mismatched effect was observed in tetrahydrofuran.