The first Pd/Cu catalyzed selective C2-alkenylation of pyridines with internal alkynes has been developed via the pyridinium salt activation strategy. Importantly, the configuration of the product alkenylpyridines could be tuned by the choice of the proper N-alkyl group of the pyridinium salts, thus allowing for both the Z- and E-alkenylpyridines synthesized with good regio- and stereoselectivity.
Evidence of a Borderline Region between E1cb and E2 Elimination Reaction Mechanisms: A Combined Experimental and Theoretical Study of Systems Activated by the Pyridine Ring
作者:Sergio Alunni、Filippo De Angelis、Laura Ottavi、Magdalini Papavasileiou、Francesco Tarantelli
DOI:10.1021/ja0539138
日期:2005.11.1
moderate increase in reactivity compared to the fluorinated substrate, despite the change in mechanism. Very interestingly, our analysis of the computed two-dimensional potential energy surface for the reaction with a F leaving group indeed evidences the lack of a net distinction between the E1cb and E2 reaction paths, which appear to merge smoothly into each other in these borderline cases.