Strong acids in CTH of mandelonitrile acetyl ester

[psygn]

Why do strong acids/elemental H2 seem to bee necessary in the CTH of mandelonitriles and their esters? What would bee the product of a CTH w/HCOOK + Pd performed on a mandelonitrile ester? Amine? Nitrile? No rxn?

What about CTH w/H2 generated in situ from NaBH4 w/ a strong acid?

Many thanks,
-psygn