Reduction of hemiaminal by triethylsilane / boron trifluoride I was trying to understand how the following reaction occurs (taken from a synthesis of homopipecolic acid[1]):

I thought that triethylsilane, $\ce{Et3SiH}$, would reduce the ester to an aldehyde. However, it turns out that the hemiaminal carbon has also been reduced with cleavage of the $\ce{C-N}$ bond. How does this happen?
References:

Chiou, W.; Chen, G.; Kao, C.; Gao, Y. Syntheses of (−)-pelletierine and (−)-homopipecolic acid. Org. Biomol. Chem. 2012, 10 (13), 2518. DOI: 10.1039/C2OB06984A.
My organic chemistry is rusty by now, but the full mechanism for the reduction itself is likely something along these lines:

In a &quot;typical&quot; lactone / ester, the alkyl oxygen can't be lost so easily, but in this case there's a nitrogen lone pair that can assist in that. The resulting iminium ion is reduced by the silane. The acid at the end will remove the remaining boron trifluoride.