Which prophets died outside Jerusalem? Jesus said that no prophet can die outside Jerusalem (Luke 13:33). Did any prophets die outside Jerusalem? If so, which ones?
The problem to solve is related to quoting Scripture out of context


  Purposely then He says nothing in answer to the idle question, but
  turns His discourse to a more important subject. ~ St Cyril  


Jesus was speaking about himself ("a prophet") in the third person

Jesus also referred to himself as "a prophet" in Mark 6:4:


  “But Jesus said unto them, a prophet is not without honour, but
  in his own country, and among his own kin, and in his own house


The context of that comment in Mark is the negative reaction to him in Nazareth.  

What's going on in Luke 13; what's the context?

Regarding Luke 13:33, a note in the New American Bible makes the following point:


  [13:33] It is impossible that a prophet should die outside of
  Jerusalem: Jerusalem is the city of destiny and the goal of the
  journey of the prophet Jesus. Only when he reaches the holy city will
  his work be accomplished.  


Consider the context of that section in Luke: Jesus is engaging in foretelling. 

Luke 13:27-35 (NAB)  


  27 Then he will say to you, ‘I do not know where [you] are from.
  Depart from me, all you evildoers!’  28 And there will be wailing and
  grinding of teeth when you see Abraham, Isaac, and Jacob and all the
  prophets in the kingdom of God and you yourselves cast out.   29  And
  people will come from the east and the west and from the north and the
  south and will recline at table in the kingdom of God. 30  For behold,
  some are last who will be first, and some are first who will be last.”
  31 At that time some Pharisees came to him and said, “Go away, leave
  this area because Herod wants to kill you.”  32 He replied, “Go and
  tell that fox, ‘Behold, I cast out demons and I perform healings today
  and tomorrow, and on the third day I accomplish my purpose. Yet I must continue on my way today, tomorrow, and the following day, for it is impossible that a prophet should die outside of Jerusalem.  34 “Jerusalem, Jerusalem, you who kill the prophets and stone those sent to you, how many times I yearned to gather your children together as a hen gathers her brood under her wings, but you were unwilling!  35 Behold, your house will be abandoned. [But] I tell
  you, you will not see me until [the time comes when] you say, ‘Blessed
  is he who comes in the name of the Lord.’”s   


What, the Bible wasn't written in English?

What is the correct rendering of the passage into English?  Good question.  If we look at bible gateway, the two most common renderings are (1) "... it is not possible/it is impossible" and (2) "... it cannot be" ... that a prophet dies outside of Jerusalem."  (More than 10 each).  Those aren't identical meanings, but they are similar enough, and most of them use "a prophet" as the subject.  (As Jesus did in Mark 6:4).  

Other ways that is has been rendered into English. (All from biblegateway).    


  AMPC ... for it will never do for a prophet to be destroyed away from
  Jerusalem!
  CJB ... it is unthinkable that a prophet should die anywhere but in
  Yerushalayim.
  CEV ... Jerusalem is the place where prophets are killed.
  DARBY ... for it must not be that a prophet perish out of Jerusalem.
  ERV ... I must go, because all prophets should die in Jerusalem.
  EXB  ... it cannot be right [is impossible; is unthinkable] for a prophet > to be killed anywhere except in Jerusalem.
  GNT ... it is not right for a prophet to be killed anywhere except in
  Jerusalem.
  PHILLIPS  ... for it would never do for a prophet to meet his death
  outside Jerusalem!
  MSG ... it’s not proper for a prophet to come to a bad end outside
  Jerusalem.
  NLV ... One who speaks for God cannot die except at Jerusalem.
  WYC ... for it falleth not [for] a prophet to perish out of Jerusalem.  


Dead prophets

At least two other prophets died outside of Jerusalem, besides the example you offer.  


Moses never made it to the promised land, so he obviously died
"outside of Jerusalem."
Jeremiah was released by the Babylonians and reportedly left for
Mizpah, and thence to Egypt.  As there is no record of his death,
nor of his return, it is most likely that he died in Egypt.   


Conclusion

Jesus is speaking of himself in the third person.  He knows that it is God's will that he die in Jerusalem.   



If you look at the commentaries of theologians who preceded Thomas Aquinas, you will find in Lectio 5 of the Cataena Aurea regarding Luke, none of them dwell on that phrase.  Their commentaries vary somewhat, but their themes and interpretations are on the bigger picture of the trials Jerusalem (where prophets are killed) has coming ... but Jesus will go on, as his Father's will directs. 

St Cyril:  


  Purposely then He says nothing in answer to the idle question, but
  turns His discourse to a more important subject.  




@AndrewShanks points out that John the Baptist, a prophet, was killed by Herod who (according to Josephus) was based in Machaerus.