title: Stereoselective reactions. XXXIV. Enantioselective deprotonation of prochiral 4-substituted cyclohexanones using chiral bidentate lithium amides having a bulky group instead of a phenyl group on the chiral carbon.
abstract: Using chiral bidentate lithium amides having a bulky group instead of a phenyl group on the chiral carbon, enantioselective deprotonation of prochiral 4-substituted cyclohexanones in the presence of excess trimethylsilyl chloride was examined in THF in the absence and in the presence of HMPA. It is shown that enantioselectivity of the reactions decreases as the substituent on the chiral carbon of the chiral lithium amides and the substituent at the 4-position of cyclohexanones become reasonably bulky. An eight-membered cyclic transition state model is proposed for this deprotonation reaction.
authors: College of Pharmacy, Nihon University, Narashinodai, Chiba, Japan.
authors: M
authors: M
authors: Toriyama
authors: K
authors: K
authors: Sugasawa
authors: S
authors: S
authors: Motohashi
authors: N
authors: N
authors: Tokutake
authors: K
authors: K
authors: Koga
mesh_terms: D003512:Cyclohexanones / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification; D007202:Indicators and Reagents; D008094:Lithium; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011522:Protons; D013237:Stereoisomerism
chemical_list: D003512:Cyclohexanones; D007202:Indicators and Reagents; D011522:Protons; D008094:Lithium