When an aldehyde or a ketone is condensed with ethyl a-chloroacetate in the presence of sodium ethoxide, the product is an α,β-epoxy ester called a glycidic ester. The synthesis is called the Darzens condensation.

(a) Outline a reasonable mechanism for the Darzens condensation.
(b) Hydrolysis of the epoxy ester leads to an epoxy acid that, on heating with pyridine, furnishes an aldehyde. What is happening here?

(c) Starting with b-ionone, show how you might synthesize the following aldehyde. (This aldehyde is an intermediate in an industrial synthesis of vitamin A.)

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R O CI EtONa OEt OEt NaCl EtOH A glycidic ester R O C.H.N heat