How to convert phenylacetic acid to 3-phenylpropionitrile?

I understand that phenylacetic acid reacts with $\ce{KSCN}$ can form phenylacetonitrile plus the side product ($\ce{CO2}$ and $\ce{KSH}$). This is Letts nitrile synthesis


However, the problem is to convert phenylacetic acid to 3-phenylpropionitrile.
Is that possible? What reagents do we need?




You need to add one carbon, the easiest source of this is as CN-.


Three steps.


1. Reduce phenylacetic acid to 2-phenylethanol (borane.THF is a good way)
2. Form the tosylate of the alcohol (TsCl, pyridine)
3. Treat the tosylate with NaCN in DMSO [reference here](https://www.gaylordchemical.com/synthesis-corner/cyanation/).


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