How to remove selected commit log entries from a Git repository while keeping their changes?

I would like to remove selected commit log entries from a linear commit tree, so that the entries do not show in the commit log.

My commit tree looks something like:

R--A--B--C--D--E--HEAD

I would like to remove the B and C entries so that they do not show in the commit log, but changes from A to D should be preserved. Maybe by introducing a single commit, so that B and C become BC and the tree looks like.

R--A--BC--D--E--HEAD

Or, ideally, after A comes D directly. D' representing changes from A to B, B to C and C to D.

R--A--D'--E--HEAD

Is this possible? if yes, how?

This is a fairly new project so has no branches as of now, hence no merges as well.