In an elaborate Ponzi scheme that lasted nearly two years, two British men persuaded investors to put up nearly $100 million in loans to wealthy wine collectors, according to federal prosecutors. But those collectors never existed, prosecutors said, and neither did the extensive reserves of valuable wine that the men promised would secure the loans. Stephen Burton, one of the men who prosecutors said ran the scheme, pleaded not guilty on Saturday to charges of wire fraud, wire fraud conspiracy and money laundering conspiracy in federal court in Brooklyn. Mr. Burton, 58, had been extradited to the United States from Morocco, where he was arrested last year after he was caught trying to enter the country using a fake Zimbabwean passport, according to prosecutors. James Wellesley, 56, is accused of conspiring with Mr. Burton. He was arrested last year and remains in extradition proceedings in Britain, prosecutors said. If convicted, the defendants each face up to 20 years in prison. John