Ionic polymer-supported O-trimethylsilyl-α,α-diphenyl-(S)-prolinols as recoverable organocatalysts for the asymmetric Michael reactions of carbon acids with α,β-enals
作者:Oleg V. Maltsev、Alexander S. Kucherenko、Sergei G. Zlotin
DOI:10.1016/j.mencom.2011.04.011
日期:2011.5
A recyclable organocatalyst bearing O -trimethylsilyl-α,α-diphenyl-( S )-prolinol unit tagged to the imidazolium cation and poly(4-styrenesulfonate) anion in the reaction of CH-acids with α,β-enals provided the respective Michael adducts in high yields (up to 99%) and with high enantioselectivities (up to 98% ee ).
<i>O</i>-TMS-α,α-diphenyl-(<i>S</i>)-prolinol Modified with an Ionic Liquid Moiety: A Recoverable Organocatalyst for the Asymmetric Michael Reaction between α,β-Enals and Dialkyl Malonates
作者:Oleg V. Maltsev、Alexandr S. Kucherenko、Sergei G. Zlotin
DOI:10.1002/ejoc.200900807
日期:2009.10
O-TMS-α,α-diphenyl-(S)-prolinol derivative bearing an ionicliquid fragment was synthesized for the first time and proven to be an efficient catalyst for the asymmetricMichaelreaction of aromatic α,β-unsaturated aldehydes with dialkylmalonates. The prepared catalyst can be recovered four times and used in the same reaction without a decrease in activity or a decrease in the enantioselectivity of
Highly enantioselective and recyclable organocatalytic Michael addition of malonates to α,β-unsaturated aldehydes in aqueous media
作者:Subrata K. Ghosh、Kritanjali Dhungana、Allan D. Headley、Bukuo Ni
DOI:10.1039/c2ob26248g
日期:——
in our lab, has been found to be very effective for the Michaeladdition reaction in aqueous solvents involving a wide range of α,β-unsaturated aldehydes and malonatederivatives. For the reactions studied, good to excellent yields (73%–96%) and high to excellent enantioselectivities (up to 97%) were obtained using this catalyst. In addition, the catalyst could be recycled up to four times with gradual
adopting a cis H2/H12b geometry has been realized by a Pictet−Spengler/lactamization cascade sequence. The absolute stereochemistry at C2, C3, and C12b was governed by the originally created chirality of the Michael adduct through organocatalyzed conjugate addition of dialkyl malonates to α,β-unsaturatedaldehydes.
Enantioselective Michael Addition of Malonates to Aromatic &#945;,&#946;-Unsaturated Aldehydes Organocatalyzed by (S)-2-[bis(3,4,5-Trifluorophenyl) trimethylsilanyloxymethyl]pyrrolidine
The Michael addition of malonates to aromatic α,β-unsaturated aldehydes was efficiently organocatalyzed by (S)-2-[bis(3,4,5-trifluorophenyl)trimethylsilanyoxymethyl]pyrrolidine, derived from L-proline to afford the corresponding adducts in good yields with good to excellent enantioselectivities.