Olefination of pyridine

Scheme 62 Pd-catalyzed ligand-promoted C3-olefination of pyridines.

Direct Alkenylation of Heteroarenes. Pivalic acid enhanced both yield and selectivity for the C2-selective olefination of pyridine. Other acid additives performed inferiorly to pivalic acid 2.5 equiv of PivOH was the ideal amount to maximize product yield. Silver(I) acetate functioned as a terminal oxidant and also positively influenced yield and selectivity. Only small amounts of C3 product were detected. 

Silver(I) salts can also function as an terminal oxidant in the C2-selective olefination of pyridine improvements in both yield and C2 selectivity were observed when less basic AgOAc was employed in place of Ag2C03 as an oxidant. Maximal yields were achievable when pivalic acid was added. Of note, only small amounts of C3 product were detected. 

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