The oxidation of aldehydes and alpha-diketones with peroxy compounds

Recently, I have been reading up on the Baeyer-Villiger (BV) oxidation. The oxidation is most commonly discussed for ketones. However, the oxidation also works for aldehydes and $$\alpha$$-diketones (Rojas, 2015).

The above image is Scheme 2.2 from Rojas (2015).

I have mainly two queries:

1. Does the oxidation of aldehydes to carboxylic acids by peroxy compounds, such as peracids, proceed via a BV oxidation where the hydride is the migrating group? This would be seemingly different from the oxidation mechanism for the oxidation by $$\ce {MnO4^-}$$ or $$\ce {CrO3}$$ where the aldehyde is oxidised when it is in the gem-diol form.

2. Why does the oxidation of $$\alpha$$-diketones yield the corresponding anhydride and not an $$\alpha$$-ketoester? This is extremely puzzling because the acyl group is terribly bad at stabilising any partial positive charges on the acyl carbon. How is it possible that such a BV oxidation can occur?

Reference

Rojas, C. M. (2015). Molecular Rearrangements in Organic Synthesis (1st ed.). Hoboken, New Jersey: John Wiley & Sons, Inc.

• 1) Hydride migrates to leave the more stable cation. 2) Acyl migrates for the same reason. – user55119 Mar 11 '19 at 2:32