We don't have synonyms for upstarting yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are upstanding, starting and unstartling.
(n) :
One who has suddenly gained wealth, power, or other prominence, but either has not received social acceptance or has become arrogant or presumptuous.
(n) :
One who has suddenly gained wealth, power, or other prominence, but either has not received social acceptance or has become arrogant or presumptuous.