Sulfone–Metal Exchange and Alkylation of Sulfonylnitriles. (19th May 2017) - Yang, Xun
Abstract: The first general sulfone–metal exchange is described. Treating substituted 2‐pyridylsulfonylacetonitriles with either BuLi or Bu3 MgLi generates metalated nitriles that efficiently intercept a variety of electrophiles to afford quaternary nitriles. The 2‐pyridylsulfone is critical for the sulfone–metal exchange because chelation anchors the organometallic proximal to the electrophilic, tetrasubstituted sulfone to override complex‐induced deprotonation. Alkylating commercial 2‐pyridinesulfonylacetonitrile with mild bases, either K2 CO3 or DBU, and subsequent sulfone–metal exchange and alkylation rapidly assembles quaternary nitriles by three alkylations, only one of which requires an organometallic reagent.