Generation and stability of N-phenacyl-4-R-pyridinium ylides in silicon polypodands

Rate constants for the deprotonation reaction of N-phenacyl-4-R-pyridinium bromides (R ¼ H, CH3, CN) with 1,4-diazabicyclo[2.2.2]octane were measured in three silicon polypodands, Me2Si24, EtSi34 and PhSi34. Silicon polypodands as open molecular capsules lower the deprotonation rates but increase the stability of the formed ylides in comparison to DMSO and water. q 2004 Elsevier B.V. All rights reserved