In order to verify the l-CJC, stereochemical assignments of the@-hydroxy ester dianion Claisen products from 7 and 13, the corresponding uC,/C, P-hydroxy esters were prepared by aldol condensation. Thus, alcohol 6 was acetylated and the resulting acetate was employed in an Ireland enolate-Claisen rearrangement. Subsequent diazomethane esterification provided methyl ester 18, the lithium enolate of which was condensed with ...
