Synthesis using Cationic Hetero-Cope Rearrangement

By searching for the reference of the synthesis below I arrived at an example of Cationic Hetero-Cope Rearrangement, but I can't access the paper. How does it work here, and what happens in the first step of the synthesis (the addition of iBuOH and TsOH at 80 degrees)?


[![enter image description here](https://i.stack.imgur.com/rhF8m.png)](https://i.stack.imgur.com/rhF8m.png)




This would be the reaction sequence:
[![enter image description here](https://i.stack.imgur.com/uhjXI.gif)](https://i.stack.imgur.com/uhjXI.gif)


 2