(1R,5S)-(+)-Nopinone of High Enantiomeric Purity

Commercial β-pinene of 87% ee can be upgraded to the 98plus;% ee level by simple treatment with silver perchlorate. A solid complex is obtained whose formation is more rapid when two like enantiomers are involved. Simple dissolution of this precipitate in water releases the enantioenriched hydrocarbon from which (+)-nopinone of high enantiomeric purity is obtained via ozonolysis.