How to synthesize 3‐cyclopentylpropanal from (chloromethyl)cyclopentane?
3 Steps:
Step 1 - react the starting material with the preformed anion of ethyl cyanoacetate (NaOEt/EtOH should do this comfortably)
Step 2 - mild base hydrolysis of the product (NaOH/EtOH) followed by acidification to remove the ethyl ester group.
Step 3 - Dibal-H reduction of the nitrile to aldehyde 1.