Replacing Josephine

[LouisFerdinand]

At the top of his list of empress replacements, though Emperor Napoleon I of the French had yet to divorce Josephine, was Grand Duchess Anna Pavlovna of Russia.   
Napoleon was prepared to offer Tsar Alexander I Poland.     
Anna Pavlovna was taken off the marriage market by her mother who thought Anna was far too young to marry.

[LouisFerdinand]

Napoleon was on a search for a suitable wife and a wife that could give him prestige for his new empire. His first thought was the Grand Duchess Anna Pavlovna. How could Emperor Alexander I consent to a marriage between his sister and his enemy?