robocopy exclude subfolders with unknown name

Question

I want to copy some folder structures that look like

+[a]
+[b]
| +[R]
| | +[xyz]
| | +[abc]
| | + a
| | + b
| +[D]
|   +[xyz]
|   +[abc]
|   + a
|   + b
+[c]
  +[R]
  | +[123]
  | |  + 2
  | |  + 3
  | |  + j
  | +[567]
  | |  + 6
  | |  + z
  | + a
  | + b
  +[D]
    +[745]
    |  + 2
    |  + 3
    |  + x
    +[234]
    |  + 6
    |  + y
    + a
    + b

names in brackets are folders.

I want to keep the file siblings of all [R] and [D] folders (they may appear on arbitrary deeply nested depths) but do not copy their sub folders (or at least not their files and further subfolders).

so in this example the R and D folders and the a,b,c should be kept and the subdirs of R and D along with their files should be removed.

I tries it with options like /xf *\R\*\* or /xd *\R\* but robocopy always complains about invalid arguments - it seems that it only can match parts of the filename and not the complete path - or at least it does not understand the path delimiter in the pattern.