Ylide-Functionalization via Metalated Ylides: Synthesis and Structural Properties

The α-metallated ylides Ph₃P?C?Z]^?M⁺ (with Z=SO₂Tol or CN and M=Na or K) were used as versatile nucleophiles for the facile access to ylide-substituted compounds. Halogenations, alkylations, carbonylations and functionalization reactions with main group element halides were easily accomplished by simple trapping reactions with the appropriate electrophiles. X-ray crystallographic studies of all compounds – including the first structures of α-fluorinated P-ylides – showed remarkable differences in the ylide backbone depending on the substituents. In the fluorinated compounds, a change from a fully planar to a pyramidalized ylidic carbon centre was observed despite the strongly anion-stabilizing ability of the yldiide substituent. π-Donation from the ylide substituent also resulted in geometric restrictions depending on the steric and electronic properties of the introduced substituents.