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Hiroaki Sasai

Publications and source records attributed to Hiroaki Sasai.

8 recordsLinked to original sources
PubMed2005

Bifunctional organocatalysts for enantioselective aza-Morita-Baylis-Hillman reaction.

The efficient and novel bifunctional organocatalyst for the enantioselective aza-Morita-Baylis-Hillman (aza-MBH) reaction has been established with (S)-3-(N-isopropyl-N-3-pyridinylaminomethyl)BINOL for the first time. The reaction proved to be deeply influenced by the position of the Lewis base attached to BINOL. The acid-base-mediated functionalities for the activation of the substrate and the fixing of conformation of the organocatalyst are harmoniously performed to promote the reaction with high enantiocontrol.

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PubMed2003

Monolayer-protected Au cluster (MPC)-supported Ti-BINOLate complex.

[reaction: see text] Disulfides bearing (R)-1,1'-bi-2-naphthol ((R)-BINOL) moieties at each terminal position have been successfully introduced on the surface of Au cluster. Ti-BINOLate complex generated from the obtained monolayer-protected Au cluster (MPC) promoted catalytic asymmetric alkylation of benzaldehyde with Et(2)Zn to afford the adduct in up to 98% yield with 86% ee. After completion of the reaction, the BINOL-functionalized MPC was easily recovered.

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PubMed2003

Polymer-supported bisBINOL ligands for the immobilization of multicomponent asymmetric catalysts.

[reaction: see text] Polymer-supported bisBINOL ligands were successfully utilized for the immobilization of multicomponent asymmetric catalysts. The polymer-supported Al-Li-bis(binaphthoxide) (ALB) catalyst was more effective than the dendrimer-supported ALB in the Michael reaction of 2-cyclohexen-1-one with dibenzyl malonate affording the adduct in 91% yield with 96% ee. The polymer was also effective for the immobilization of a mu-oxodititanium complex that promoted carbonyl-ene reaction of ethyl glyoxalate with alpha-methyl styrene to provide the adduct with up to 98% ee.

Journal Article↗
PubMed2003

Synthesis of new chiral bis(isoxazoline) ligands containing spiro[5.5]undecane skeleton.

New chiral bis(isoxazoline) ligands bearing a spiro[5.5]undecane skeleton were designed and synthesized in five steps from diethyl malonate (3). These ligands showed a coordinating ability to Cu(II) as chiral ligands. A complex of (+)-(M*,S*,R*)-[5.5]-SPRIX 2b and Cu(OTf)(2) catalyzed the conjugate addition of diethyl-zinc to 2-cyclohexenone (8) to give (S)-3-ethyl-cyclohexanone (9) in 93% yield with 54% ee.

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