Littlejohn & Co. LLC, a private investment firm based in Greenwich, Conn., said it agreed to sell CTI Foods to Thomas H. Lee Partners and an affiliate of Goldman Sachs. CTI Foods is a provider of custom food solutions to chain restaurants in North America. Littlejohn acquired CTI in 2010 and has since expanded the company into a national provider. During that time, CTI built a state-of-the-art soup plant and research and development facility, completed two acquisitions, and diversified its customer base.