Reading through a patent on the synthesis of the 1,3-diol part of statins, I found they transform a terminal CN group to an aldehyde. I know you can reduce the nitrile to give aldehydes by several methods but since the molecules has an ester group they don't want to risk the reduction of the ester.
They use oxalyl chloride and dmso in DCM and then Et3N classic Swern oxidation conditions but can't figure out how that works...
Any thoughts where the oxygen might come from? would it go through the intermediate I draw?
Thanks