Asymmetric induction catalyzed by conjugate bases of chiral proton acids as ligands: Enantioselective addition of dialkylzinc-orthotitanate complex to benzaldehyde with catalytic ability of a remarkable high order

Asymmetric ethylation of aromatic aldehyde by diethylzinc in the presence of chiral auxiliaries derived from (S)-[4-HOC6H4CH2CH(NH2)CPh2OH]

“…Yoshioka et a1. 8 showed, by 'H NMR spectroscopy, that Et2Zn and Ti(OPr'), can take part in exchange reactions to form ethyltitanium species. The intermediacy of mixed titanium/zinc complexes have also been proposed …”

“…8 The addition sequence used in Method D was (i) (l), (ii) ArCHO, (iii) Ti (OPr'), and (iv) Et,Zn. This should lead to the initial formation of the chiral Schiff's base (6), which would react further with Ti(OPri)4 to give (11).…”

Elucidation of the absolute configuration of JNJ‐27553292, a CCR2 receptor antagonist, by vibrational circular dichroism analysis of two precursors

“…(3). A 3 liter flask was charged with 1 liter of dry toluene, the catalyst (2 g, 0.0053 mol), and Ti(i-PrO) 4 (193 g, 0.68 mol) and the resulting solution was degassed by three freeze-thaw cycles under argon. This solution was then heated to 408C for 20 min, then cooled to À788C.…”

“…After 4 h the reaction mixture was carefully quenched by addition of 1 M HCl. The aqueous layer was extracted with CH 2 Cl 2 and the combined organic phases were filtered through celite, washed with water, dried over MgSO 4 (5). A solution of the azide 4 (50 g, 0.217 mol) in methanol (800 ml) and Pt/C 5% (2 g) was placed in a Parr apparatus and flushed with three cycles of vacuum/ hydrogen.…”

“…[3][4][5] Although 1-(3 0 ,4 0 -dichlorophenyl)-propanol (3) has not been described before, very close analogues (phenyl and 4 0 -chlorophenyl) have been published. 4,5 The more active enantiomer of 1 was found to be (À)-1, derived from amine (À)-5, which by analogy with the published data should have the S configuration.…”