Alberto W. Vilar, who was a major benefactor of American orchestras and opera houses, “was sent to jail on Thursday. Convicted of 12 counts related to securities fraud on Nov. 19, Mr. Vilar had been free on bail pending his sentencing March 20. But federal prosecutors argued that Mr. Vilar was a flight risk given the prospect of a lengthy prison term and what they called his penchant for lying and stealing.”