Stereochemistry of enantioselective deprotonation of 4-substituted cyclohexanones by chiral bidentate lithium amides

Abstract

Enantioselective deprotonation of 4-substituted cyclohexanones ( 1) in the presence of excess trimethylsilyl chloride was examined using chiral bidentate lithium amides ((R)- 3∼(R)- 7) in THF. The solution structures of (R)- 3a in THF in the presence and in the absence of lithium chloride were studied by NMR. It is concluded that the eight-membered cyclic transition state ( 10) offers reasonable explanation of the stereochemical course of the present reaction using (R)- 3a.