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
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.
MacMillan catalyst was modified with imidazolium ionic liquid by ester linkage and acts as recoverable and reusable catalyst for asymmetricDiels–Alder reactions. A Diels–Alder reaction between cyclopentadiene and crotonaldehyde was carried out using MacMillan catalyst modified with ionic liquid (5 mol%) using trifluoroacetic acid (5 mol%) as co-catalyst in acetonitrile–water (95 : 5) at room temperature
Camphor Sulfonyl Hydrazines (CaSH) as Organocatalysts in Enantioselective Diels−Alder Reactions
作者:Hao He、Bao-Jian Pei、Ho-Hsuan Chou、Tian Tian、Wing-Hong Chan、Albert W. M. Lee
DOI:10.1021/ol8005826
日期:2008.6.1
Cyclic sulfonyl hydrazine was demonstrated for the first time as a new functionality for organocatalysis. A series of six-membered cyclic hydrazines derived from camphor sulfonic acid were synthesized. With trichloroacetic acid as cocatalyst, they are efficient organocatalysts for enantioselectiveDiels-Alderreactions with good chemical yields and up to 96% ee. The reactions took place in brine at