Freeport-McMoRan Inc.'s bondholders are creating a potential obstacle for a $2 billion asset sale designed to inject cash into the debt-laden commodities producer, according to people with knowledge of the matter. Some of the creditors want more money and greater protection for allowing the sale of oil and gas assets to Anadarko Petroleum Corp. -- a proposal that requires changes to Freeport's existing agreement with the lenders. Freeport, which wants to keep the debt on its own balance sheet even as the assets shift to the buyer, is seeking majority approval from five sets of bondholders who together own $2.3 billion of notes to complete the asset sale.