was suitable for bulkier substrates (sterictuning of the catalyst). Using the La-NMe-linked-BINOL complex, the Michaelreaction of methyl acetoacetate (8a) to 2-cyclohexen-1-one (7b) gave the corresponding Michael adduct 9ba in 82% yield and 92% ee. The linker heteroatom in linked-BINOL is crucial for achieving high reactivity and selectivity in the Michaelreaction of beta-keto esters. The amine moiety
Enantioselective Michael Reaction Catalyzed by Well-Defined Chiral Ru Amido Complexes: Isolation and Characterization of the Catalyst Intermediate, Ru Malonato Complex Having a Metal−Carbon Bond
Chiral Ru amido complexes promote asymmetric Michael addition of malonates to cyclic enones, leading to Michael adducts with excellent ee's, in which the chiral Ru amido complexes react with malonates to give isolable catalyst intermediates, chiral Ru malonato complexes bearing a metal bound C-nucleophile.
-amino acid into L-Leu-based heptapeptides preferentially induced right-handed (P) helical structures. Using 5∼20 mol % of a single helical foldamers-catalyst, enantioselective 1,4-addition reactions of dialkyl malonates to cycloalk-2-enones (5∼7 rings) proceeded to give chiral 3-substituted cycloalkanones with 94∼99% ee in moderate chemical yields, regardless of the ring size of substrates.
A TiCl4-promoted domino semipinacolâSchmidt reaction of oxaspiropentane-azide provides an easy access to bridged azatricyclic ring systems, which possess the azaquaternary center, present in the immunosupressant FR901483 and platelet aggregation inhibitor daphlongeranine B.
通过 TiCl4 促进的多米诺半联苯酚施密特反应,可以很容易地获得桥接的氮杂环系统,该系统具有氮杂四元中心,存在于免疫抑制剂 FR901483 和血小板聚集抑制剂达夫龙葵碱 B 中。