Complex sentence: In January 1987, Robert Kraft and Steve Karp purchased an option on the track, which would allow Kraft, who had tried unsuccessfully to purchase the Patriots, to prevent the financially struggling Sullivans from hosting non-Patriot events at the stadium during races.
Split into simpler sentences: In January 1987, Robert Kraft and Steve Karp purchased an option on the track, which would allow Kraft, who had tried unsuccessfully to purchase the Patriots. Purchasing the track would allow him to prevent the financially struggling Sullivans from hosting non-Patriot events at the stadium during races.