Question

Using your roadmaps as a guide, show how to convert 2-oxepane and ethanol into 1-cyclopentenecarbaldehyde.You must use 2-oxepane as the source of all carbon atoms in the target molecule. Show all reagents and all molecules synthesized along the way.

Short answer

Answer: The synthesis of 1-cyclopentenecarbaldehyde from 2-oxepane and ethanol can be achieved through a sequence of ring-opening, oxidative cleavage, and aldehyde formation reactions, followed by nucleophilic attack by ethanol and a dehydration step. The key steps involve breaking the 7-membered ring into a 5-membered ring and a linear fragment, removing two carbons from the linear fragment to form an aldehyde, and combining ethanol and the aldehyde to form the final product.

Step-by-step solution

Analyze the structures of reactants and product

Let's analyze the structures of 2-oxepane (C6H10O), ethanol (C2H5OH), and 1-cyclopentenecarbaldehyde (C6H8O) 2-oxepane: 7-membered ring with an oxygen atom Ethanol: Simple 2-carbon alcohol 1-cyclopentenecarbaldehyde: 5-membered ring with a double bond and an aldehyde group

Break the 7-membered ring into a 5-membered ring and a linear fragment

To achieve the 5-membered ring in the product molecule, we will first need to break the 7-membered ring in 2-oxepane. We can do this by reacting 2-oxepane with an electrophilic species to break the C-O bond and generate a 5-membered ring and a linear fragment.

Remove two carbons from the linear fragment

We will now remove two carbons from the linear fragment to obtain an aldehyde group. This can be achieved through oxidative cleavage using ozone (O3), followed by a reduction step with dimethyl sulfide (DMS) or hydrogen peroxide (H2O2) to produce the aldehyde. The net reaction is as follows: 2-oxepane + O3 -> 1-cyclopentenecarboxaldehyde + 2-carbon fragment 1-cyclopentenecarboxaldehyde + DMS/H2O2 -> 1-cyclopentenecarbaldehyde

Combine ethanol and the aldehyde to form the final product

To complete the synthesis, we will use ethanol as a nucleophile to attack the aldehyde, followed by a dehydration reaction to form the final product, 1-cyclopentenecarbaldehyde. The series of reactions can be represented as follows: 1-cyclopentenecarbaldehyde + ethanol -> hemiacetal intermediate hemiacetal intermediate -> 1-cyclopentenecarbaldehyde (dehydration) In summary, we have shown the steps for converting 2-oxepane and ethanol into 1-cyclopentenecarbaldehyde using 2-oxepane as the source of all carbon atoms in the target molecule. This synthesis can be achieved through a sequence of ring-opening, oxidative cleavage, and aldehyde formation reactions, followed by nucleophilic attack by ethanol and a dehydration step to form the final product.