(Mac‐SILC) in the pores of silica gel with the aid of an ionic liquid – 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide. The heterogenized organocatalyst was utilized for the enantioselectiveDiels–Alder reaction of cyclopentadiene and cinnamaldehyde, recovered by simple filtration and subsequent evacuation, and repeatedly used up to six times in 81% average chemical yield, 87% ee for endo‐
liquid-supported imidazolidinone catalyst I in enantioselectiveDiels–Alderreactions was investigated. The Diels–Alderreactions involving α,β-unsaturated aldehydes and cyclopentadiene proceeded efficiently in the presence of catalyst I to provide the desired products in moderate to good yields with good to excellent enantioselectivities. Especially noteworthy, catalyst I can be recovered and reused
Structural effects in pyrazolidinone-mediated organocatalytic Diels–Alder reactions
作者:Eoin Gould、Tomas Lebl、Alexandra M.Z. Slawin、Mark Reid、Andrew D. Smith
DOI:10.1016/j.tet.2010.09.021
日期:2010.11
promoted Diels–Alderreactions evaluated. Systematic variation of the C(5)- and N(2)-substituents indicates that the incorporation of an electron withdrawing substitutent at N(2) and either a Ph or CF3 substitution at C(5) results in optimal catalytic activity. The diastereoisomeric resolution of a model C(5)-Ph substituted pyrazolidinone and its ability to impart modest levels of asymmetric induction
Aqueous Enantioselective Organocatalytic Diels−Alder Reactions Employing Hydrazide Catalysts. A New Scaffold for Organic Acceleration
作者:Mathieu Lemay、William W. Ogilvie
DOI:10.1021/ol051476w
日期:2005.9.1
[reaction: see text] Cyclic hydrazides function as asymmetric organocatalysts in aqueous Diels-Alderreactions. The hydrazide is employed as the catalytic machinery in a compact camphor-derived framework that imparts facial selectivity to the cycloadditions. Kinetic evidence suggests the reaction involves rapid iminium formation.