ChemInform Abstract: Useful Chiral Lactones Derived from cis‐Bicyclo(3.3.0)octan‐3,7‐dione via Asymmetric Deprotonation.

Abstract

1991 stereochemistry stereochemistry (general, optical resolution) O 0030 -078Useful Chiral Lactones Derived from cis-Bicyclo(3.3.0)octan-3,7-dione via Asymmetric Deprotonation.-Treatment of the meso ketone (I) with either of the chiral lithium amide bases shown in the scheme gives access to the two enantiomeric enolates, which are trapped with (II) or (VI) to give (III), (VII) and their enantiomers. Higher yields and enantioselectivities are obtained by the second procedure, i.e. by in situ trapping of the enolates with (VI). The derived lactones of type (V) and (VIII), besides being useful intermediates for asymmetric synthesis, also serve as stable derivatives for the determination of the e.e. values by means of NMR chiral shift techniques. -(LEONARD, J.; HEWITT, J. D.; OUALI, D.; RAHMAN, S. K.; SIMPSON, S. J.; NEWTON, R. F.; Tetrahedron: Asymmetry 1 (1990) 10, 699-702; Dep. Chem., Univ. Salford, Salford M5 4WT, UK; EN)