On most days, Tiangang Sun gets moving at 5:30 a.m. After a half-hour of pushups and jogging, a perfunctory porridge breakfast and a scouring of Chinese news sites, he begins making phone calls to business and legal contacts in China. By late morning, with his overseas associates having gone to bed, he starts ringing attorneys in Los Angeles.

Sun spends five to eight hours a day strategizing like this, usually skipping lunch. Yet, other than an occasional trip to a law office, he has limited face-to-face contact with the outside world. Even his morning jog is confined to the backyard, which has been screened by a security firm.

From the anonymity of a San Gabriel Valley home, the former oil tycoon has launched a one-man crusade against one of the world’s largest companies, Chinese energy giant Sinopec Ltd. Sun, who claims to be among China’s irst self-made billionaires, says the state-owned company seized his assets and conspired to imprison him after a business dispute. He has filed for asylum in the United States and has taken Sinopec to federal court in Los Angeles, where he is seeking $5.2 billion.

“There has to be somewhere in the world that I can get justice,” said Sun, speaking through a translator at the downtown L.A. offices of law firm Arent Fox. “I’m not going to stop fighting.”

The case faces issues of the appropriateness of United States courts as a venue for overseas business disputes, experts said. Sinopec, which did not return requests for comment, has claimed in court filings that U.S. law does not apply to the case and that U.S. courts do not have jurisdiction. It has further denied the charges. A judge will hear its motion to dismiss March 3.

Legal experts said it is not uncommon for people to bring cases over foreign assets in U.S. courts, and some have been successful. But in recent years the U.S. Supreme Court has sought to limit the reach of U.S. law. Experts also noted that the size of Sun’s alleged losses, the extremity of his allegations and the challenges posed by his case are rare.

“I was struck by the number of legal hurdles he’ll have to get over,” said David Cinotti, an attorney specializing in international dispute resolution at Venable’s New York office who reviewed the case for the Business Journal. “I haven’t seen a case like that, with a plaintiff applying for asylum.”