Complex sentence: Scotti's American debut came in the fall of 1899, when he sang in Chicago; on December 27 of the same year he made his first appearance at the Metropolitan Opera, singing the title role in "Don Giovanni".
Split into simpler sentences: Scotti's American debut came in the fall of 1899, when he sang in Chicago. On December 27 of the same year he made his first appearance at the Metropolitan Opera, singing the title role in "Don Giovanni".