Ellie Greenwich, one of the most prolific hitmakers of the 1960s, who was the co-writer of such catchy and enduring pop hits as "Be My Baby," "Chapel of Love," "Da Doo Ron Ron" and "Leader of the Pack," and who was credited with launching the career of singer Neil Diamond, died Aug. 26 of a heart attack at Roosevelt Hospital in New York, where she was being treated for pneumonia. She was 68.