Originally Posted by: will.oconnor17

The chord progression is going from a C major to an F major and the song is supposedly key of C but all the intervals being used in this section seem like they're straight from the key of F.

[p]Good observation! Using the minor 7th scale degree in a major key is what gives music a characteristically bluesy sound. That's exactly what the Stones were going for here.

In more theorectical terms it's a way of voice leading the chord change from C to F. Essentially it's like making the C into a C7(c-e-g-b-flat) which is the V (dominant five chord) of F. So you are starting in C, but then making the C a C7 chord, briefly modulating to F major.

Hope that makes sense!