help with variables inside alist

[GH]

I need some like this:

#+begin_src elisp

(let ((A "str1")
      (B "str2"))
  (setq example
        '((sexp1 (("str3" . A)
                  ("str4" . A)))
          (sexp2 (("str5" . B)))))
  ... )
  
#+end_src

But it set variables A and B as 'A and 'B instead "str1" and "str2"

How can I do?