My question concerns the relative stability of a radical next to an ester oxygen compared to a radical next to an ester carbonyl carbon.
The stabilizing effect of the electron pairs of ether oxygen is known, but the situation may be different for an ester oxygen, which donates fewer electron density.
On the other hand, can the pi electrons of the carbonyl contribute to the stabilization of the radical next to it?
What is the preferred point for a radical attack on such a (poly)ester structure and, in your opinion, is there a clear preference? References are welcome.