The chiral, non-racemic title acids are converted to methyl dioxolane-(cJ 13), oxazoline-(4) and oxazolidinecarboxyiates (cf 9). Deprotonation by Li (i-Pr), N at dry-ice temperature gives solutions of the lithium enolates AD with exocyclic enolate double bonds. These are stable enough with respect to 8-elimination (Scheme I) to be alkylated with or without cosolvents such as HMPA or DMPU. The products are formed in good to excellent yields and, with the ...
