Total synthesis of (+)-prelog-djerassi lactonic acid

Optically active Prelog-Djerassi Lactonic Acid $\text{1}$ was synthesized from D-glucal: the crucial point being the elaboration of the carboxylic group as shown in eq. 1 and 2 which involve the sequential process [i] asymmetric addition of methyl anion onto the hetero-olefin 2, [ii] trapping the carbanion intermediate $\text{3}$ [E=Li to SePh] and [iii] oxidative hydrolysis of $\text{3}$$\text{via}$ sila-pummerer rearrangement into $\text{4}$.