I'm solving some synthesis problems for practice and I came across this one:
I thought of going for compound A to B(aldehyde) with this procedure:
- $\ce{t-BuOK}$
- $\ce{BH3,THF,NaOH,H2O2}$
- $\ce{PCC,CH2Cl2}$
For the second path, in order to get to a lactone, I don't know what to do. I see that the carbonyl bond is moved to another carbon. I've learnt a way, in order to get an ester, is to add an alcohol $\ce{ROH}$ to an acyl chloride. But I'm so confused.