181230-79-5Relevant academic research and scientific papers
Chiral ligands derived from abrine. Part 7: Effect of O, S, N in aromatic ring substituents at C-1 on enantioselectivity induced by tetrahydro-β-carboline ligands in diethylzinc addition to aldehydes
Zhu,Zhao,Zuo,Pittman Jr.,Dai,Hao
, p. 2613 - 2619 (2001)
The effect of O, S and N atoms in aromatic ring substituents at C-1 position of tetrahydro-β-carboline ligands on the enantioselectivity of diethylzinc additions to benzaldehyde was studied when esters or tertiary alcohol functions were present at C-3. A mechanism is proposed to explain why the ester ligands 2c and 2d, in which the pyridyl N atom is at C′-2 in 2c and at C′-3 in 2d, catalyzed the addition of diethylzinc to benzaldehyde to form the (R)- and (S)-enantiomers of 1-phenyl-1-propanol, respectively. An explanation was also proposed for the moderate enantioselectivity induced by tert-alcohol 3c versus the very small enantioselectivity induced by 3d, containing a 3-pyridyl function at C-1, during diethylzinc additions. A -CH2-t-Bu substituent at C-1 leads to very high enantioselectivities.
Chiral ligands derived from Abrine 8. An experimental and theoretical study of free ligand conformational preferences and the addition of diethylzinc to benzaldehyde
Zhu,Jiang,Saebo,Pittman Jr.
, p. 261 - 267 (2005)
(Chemical Equation Presented). Three structurally similar series of 1,2,3,4-tetrahydro-β-carboline ligands, 4a-d, 6a-d and 7a-d, and two series of chiral oxazolidines, 8a-d and 9a-g, were synthesized and used as chiral catalysts in the addition of diethyl
