Abstract A spiro bisphosphine oxide (SpinPO) was found to be an efficient chiral Lewis base catalyst in asymmetric reductive aldol reaction of enones and aldehydes in the presence of trichlorosilane as the reductant, affording a variety of β-hydroxyketones in good yields with moderate to high levels of diastereo- and enantioselectivities.
作者:Teruaki Mukaiyama、Nobuharu Iwasawa、Rodney W. Stevens、Toru Haga
DOI:10.1016/s0040-4020(01)82423-6
日期:1984.1
A highly diastereoselective cross aldolreaction is developed using divalent tin enolates formed from stannous trifluoromethanesulfonate and carbonyl compounds. The reaction is extended to a highly enantioselective cross aldolreaction employing chiral diamines derivedfrom (S)-proline as ligands.
Remarkable Dependence of Diastereoselectivity on Anhydrous or Aqueous Solvent in the Indium Hydride Promoted Reductive Aldol Reaction of α,β-Unsaturated Ketones
作者:Katsuyuki Inoue、Tatsuya Ishida、Ikuya Shibata、Akio Baba
Dichloroindium hydride generated by the transmetallation between tributyltin hydride and indium trichloride predominantly reduced α,β-unsaturated ketones (enones) with 1,4-selectively even in the presence of aldehydes. Under anhydrous conditions, the successive aldolreaction between the resulting enolates and the remaining aldehydes proceeded with high anti-selectivity. The stereochemistry was dramatically
For the enantioselective borohydride reduction of carbonyl compounds catalyzed by the optically active ketoiminatocobalt complexes, chloroform has been employed as a unique solvent for achieving a high enantioselectivity, whereas it was found that a catalytic amount of chloroform effectively activated the present catalytic system to convert various ketones into the corresponding reduced product with a high ee in the THF solvent.
enolates which afford syn-α-iodethyl-β-hydroxyketones stereoselectively upon subsequent reaction with various aldehydes. The aldol adducts are cyclized into trans-acyltetrahydrofurans in good yield by active alumina. In contrast, the use of Et2AlI in place of TiCl4-n-Bu4NI provides the corresponding anti aldol adducts with high stereoselectivity. These methods can complementarily provide both syn and