There is a rather helpful paper from Merck Process group from 1997:
I repeated the procedure with Alloc -protected piperidine carboxaldehyde. Without the final mesylation, I got the NH indoline in the incredible yield 37% after some tedious workup (acidic extraction of the product into water etc., then a big column) and the product then crystallized nicely. The final compound was completely inactive in our project. But the joy of spiroannelation – priceless.