Solvent effects in asymmetric hetero Diels-Alder and ene reactions

Catalytic Asymmetric Inverse-Electron-Demand Hetero-Diels-Alder Reactions.

In this review, the recent developments in catalytic asymmetric inverse-electron-demand hetero-Diels-Alder reaction, which is recognized as one of the most powerful routes to construct highly functionalized and enantioenriched six-membered heterocycles, are described. The article is organized on the basis of different kinds of electron-deficient heterodienes, including α,β-unsaturated ketones/a...

Asymmetric hetero-Diels-Alder reaction catalyzed by dirhodium(II) carboxamidates.

Chiral dirhodium(II) carboxamidates are highly efficient catalysts for reactions between a variety of aldehydes and activated dienes. Catalyst loadings as low at 0.01 mol % have been realized with enantioselectivities up to 97%. Kinetic investigations reveal a pronounced electronic influence on the rate of the hetero-Diels-Alder reaction with a Hammett rho value of +1.9 (versus sigma(+)). Inhib...

Catalytic, Enantioselective Hetero-diels-alder Reactions of Aldehydes

Hetero-Diels-Alder reactions of hetaryl-thiochalcones with acetylenic dienophiles

Hetaryl-substituted thiochalcones react with acetylenic monoand diesters in the THF solution in the presence of LiClO4 at 65°C to give, after 24h, 4H-thiopyran carboxylates and dicarboxylates, respectively, in moderate to good yields. The same reactions were performed also in the THF solution without a catalyst under microwave irradiation. In that case, the reaction time was reduced to three mi...

N-heterocyclic-carbene-catalyzed asymmetric oxidative hetero-Diels-Alder reactions with simple aliphatic aldehydes.

N-heterocyclic carbene (NHC) catalysis has emerged as a powerful tool for synthesis. Among its involvement in several cycloaddition-type reactions for the construction of lactams and lactones, which are abundant in biologically active molecules and broadly used as synthons for complex molecules, NHC catalysis through formal [3+3] or [4+2] strategies is noteworthy. In particular, [4+2] cycloaddi...