X b; X= OMe loa, X= H lla, X= H b, X= OMe b, X= OMe silica gel. Column chromatography on solvent-wetted Si02 was an effective procedure for isolating pure enamino ester. Note that it was crucial to use the prescribed volumes of THF and KzCO3 solution. Otherwise, emulsions would form and the clear, Zn2+-free THF layer would not separate, making the workup tedious and decreasing the yield. For each mole of zinc salt produced, the cooled ...
