Conjugate addition of nitroalkanes to α,β-unsaturated carbonyl compounds occurs in the presence of basic alumina without a solvent. Yields are fair to good also with substrates which are acid or base sensitive.
Catalytic Asymmetric Conjugate Addition of Nitroalkanes to Cycloalkenones
作者:Stephen Hanessian、Vinh Pham
DOI:10.1021/ol000170g
日期:2000.9.1
Nitroalkanes add to cyclic and acyclic enones in an enantioselective manner in the presence of catalytic quantities of L-proline and trans-2,5-dimethylpiperazine as excess additive.
Asymmetric multifunctional organocatalytic Michael addition of nitroalkanes to α,β-unsaturated ketones
作者:Pengfei Li、Yongcan Wang、Xinmiao Liang、Jinxing Ye
DOI:10.1039/b804540b
日期:——
Cinchona alkaloid derived primary amine thioureas organocatalyzed Michael addition of nitroalkanes to enones in good yield and up to 98% ee and offered a new way to construct quaternary stereocenters from enones and nitroalkanes.
Long chain dicationic ammonium salts (1a-1c), easily prepared from tert-amines and dihaloalkanes, were successfully used as efficient phase-transfer catalysts in the Michael addition reaction of various active methylene compounds to 2-cyclohexenone without solvent under ultrasonic irradiation. The investigated dicationic salts were more effective than monocationic tetrabutylammonium bromide, with short reaction times and high yields. This methodology was established under phase-transfer catalytic conditions and ultrasonic effects with many advantages, including the easy and cost-effective synthesis of the catalyst, mild reaction conditions, short reaction times, good yields, simple work-up procedures, and environmental friendliness.
Use of a solid hydrotalcite structure incorporating fluorides for basic catalysis of michael or knoevenagel reactions
申请人:Figueras Francois
公开号:US20050250963A1
公开(公告)日:2005-11-10
The invention concerns the use of a solid basic catalyst comprising a hydrotalcite structure wherein part at least of the compensating anions are fluoride anions F
−
for producing Knoevenagel of Michael condensation reactions. The invention also concerns novel solid basic catalysts comprising a hydrotalcite structure characterised by a Mg/Al molar ratio ranging between 2.5 and 3.8 wherein at least part of the compensating anions are fluoride anions F
−
, and methods for preparing said novel catalysts.