The Collaborative International Dictionary of English v.0.48:

Whereupon \Where`up*on"\, adv.
   Upon which; in consequence of which; after which.
   [1913 Webster]

         The townsmen mutinied and sent to Essex; whereupon he
         came thither.                            --Clarendon.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "whereupon":
   after which, at what time, at which, at which time, hereinafter,
   in what period, in which time, on, on what occasion,
   on which occasion, upon, upon which, what time, when, when as,
   whenever, whereat, wherefore, whereon, whereto, whereunto,
   wherewith