Chapter 3.4, Problem 20P

(racemic) 19.84 Using your reaction roadmaps as a guide, show how to convert 2-oxepanone and ethanol into 1-cyclopentenecarbaldehyde. You must use 2-oxepanone as the source of all carbon atoms in the target molecule. Show all reagents and all molecules synthesized along the way. & + EtOH H 2-Oxepanone 1-Cyclopentenecarbaldehyde

R₂ R₁ R₁ a R Rg Nu R₂ Rg R₁ R R₁₂ R3 R R Nu enolate forming R₁ R B-Alkylated carbonyl species or amines Cyclic B-Ketoester R₁₁ HOB R R₁B R R₁₂ B-Hydroxy carbonyl R diester R2 R3 R₁ RB OR R₂ 0 aB-Unsaturated carbonyl NaOR Aldol HOR reaction 1) LDA 2) R-X 3) H₂O/H₂O ketone, aldehyde 1) 2°-amine 2) acid chloride 3) H₂O'/H₂O 0 O R₁ R₁ R R₁ R₁₂ Alkylated a-carbon R₁ H.C R₁ H.C Alkylated methyl ketone acetoacetic ester B-Ketoester ester R₁ HO R₂ R B-Dicarbonyl HO Alkylated carboxylic acid malonic ester Write the reagents required to bring about each reaction next to the arrows shown. Next, record any regiochemistry or stereochemistry considerations relevant to the reaction. You should also record any key aspects of the mechanism, such as forma- tion of an important intermediate, as a helpful reminder. You may want to keep track of all reactions that make carbon-carbon bonds, because these help you build large molecules from smaller fragments. This especially applies to the reactions in…

Provide the reasonable steps to achieve the following synthesis.