N-Alkylimidazole-Decorated Dendritic Catalysts for Baylis-Hillman Reaction

Baylis-Hillman reaction - N-alkylated imidzoles - dendrons - heterogeneous catalysis

Significance

<P>Polymer-supported dendritic ­catalysts [Gn(E-Im), Gn(A-Im), Gn(T-Im)] were ­prepared from Wang resins and N-alkylated imidazoles (1-3), and applied to the Baylis-Hillman reaction. Thus, the Baylis-Hillman reaction of methyl vinyl ketone and 4-nitrobenzaldehyde was performed with the catalytic resin G2(A-Im) (0.1 mmol of N-alkylated imidazole units) in DMF-H₂O (9:1, v/v) at room temperature for 4 h to afford ­adduct 4 in 91% yield.</P>

Comment

<P>The addition of water improved the catalytic activity in the Baylis-Hillman reaction. The second-generation catalysts [G2(E-Im), G2(T-Im), G2(A-Im)] exhibited higher catalytic activity than their non-dendritic counterparts [G0(E-Im), G0(T-Im), G0(A-Im)].</P>