Mildly basic workup

Cl2(Cy3P)2Ru=CHPh, CH2CI2, reflux. The enamide is produced. RuClH(CO)(PPh3)3 is similarly an effective catalyst for this isomerization (87-95% yield). The enamide is cleaved by oxidation with RuCl3-NaI04 followed by a mildly basic workup (40-78% yield). ... 

Collapse of the CTI forms the neutral P-keto ester product that will eventually be isolated, but the reaction mechanism does not stop here. Since the 1,3-dicarbonyl product has a highly acidic alpha proton (a to two EWGs), it becomes deprotonated in the basic reaction conditions to give a stabilized enolate. This deprotonation step is a necessary one, as it drives the equilibrium in the forward direction the Claisen condensation will not occur if there are not at least two alpha protons present in the ester starting material, and the acid-catalyzed Claisen condensation does not exist. Upon treatment with a mild aqueous workup, the enolate is protonated and the neutral P-keto ester product can be isolated. 

Both of the syntheses shown are reasonable. The reaction conditions are identical and both have commercially available starting materials. Since no regiocontrol is needed for the deprotonation, the starting materials can simply be mixed together with sodium ethoxide in ethanol (note that the alkoxide base is chosen to match the ester or carbonate leaving group). A mild aqueous workup is needed to neutralize the TM, which will be formed as the stabilized enolate in these basic reaction conditions. 

Treatment of aldehyde acetals with EtsSiOTf and 2,6-lutidine or 2,4,6-collidine at 0 °C followed by an aqueous workup achieves efficient deprotection of the acetals to the corresponding aldehydes [92]. This deprotection proceeds under weakly basic, very mild conditions with high chemoselectivity. A variety of functionalities can survive under these conditions. Aldehyde acetals are deprotected predominantly in the presence of ketone acetals. The reaction mechanism involves the formation of pyridinium-type salts such as (53) and (54). Mixed acetals can be efficiently prepared by quenching the pyridinium-type intermediate with alcohols (Scheme 9.31). 

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