A Mechanistic Puzzle

An interesting formation of the piperidine ring occurs when the alkynamine is oxidised with m-CPBA, the initial N-oxide undergoing quite a few changes before the final product is formed.  Can you work out a plausible mechanism?

For the answer see Cui L et al, J Am Chem Soc, 2009, 131, 8394-5.

The procedure can be combined with the critical alkylation of the amine with 3-butynyl tosylate.