Synthesis via oxazolines. VII. Asymmetric reduction of ketones with chiral hydride reagents

Asymmetric reduction of acetophenone with lithium aluminum hydride complexes of terpenic glycols

“…The product was recrystallized twice from hexane. After drying overnight in an evacuated desiccator over CaS04, the product weighed 7.9 g and had mp 77-78 °C; [a]29D +8.2 ± 0.6°(c 42.0, acetone); IR (Nujol mull) 3.02 (s), 6.95 (s), 7.32 (s), 7.53 (m), 8.60 (s), 9.38 (s), 9.97 (m), 10.64 (m), 10.78 (s), 13.60 µ (m) (lit.11 [ ] + 14°, mp 77.5 °C). Attempts to recover additional product 1 from the mother liquor by recrystallization or bisulfite washing were unsuccessful.…”

“…2,10-Pinanediol (7). By a published procedure,15 28 g of (-)-ßpinene (Aldrich Chemical, [ ]30 -20°) was oxidized in 2-propanolwater with 30 g of KMn04.…”

β‐Hydroxyamide‐Based Ligands and Their Use in the Enantioselective Borane Reduction of Prochiral Ketones

“…Among the variety of asymmetric reactions leading to enantiomerically pure alcohols, the enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand has received considerable attention. Among them, oxazaborolidine synthesized by Itsuno et al 3,6 from L-valine gave high enantioselectivity for prochiral ketone reduction. 4,5 Apart from transition metal complexes, many researchers started working with hydride donors like aluminum and boron complexes.…”

“…4,5 Apart from transition metal complexes, many researchers started working with hydride donors like aluminum and boron complexes. Among them, oxazaborolidine synthesized by Itsuno et al 3,6 from L-valine gave high enantioselectivity for prochiral ketone reduction. This method was further developed by Corey et al [7][8][9][10][11] which is generally known as the CBS method.…”

Asymmetric reduction with chiral reagents from lithium aluminum hydride and (S)-(-)-N-(o-substituted benzyl)-.alpha.-phenylethylamines

“…A systematic study of the effect of functional group substituents on the chiral amine ligands should afford a better understanding of the mechanism of these asymmetric reductions as well as the necessary information for the design of a more effective chiral amine-LiAlH4 reagent. We have begun such a study using various chiral secondary amines (3)(4)(5)(6)(7)(8) for the reaction with L1AIH4 in various molar ratios. The effect of three achiral complexing additives also has been studied.…”