Complex sentence: While at Toronto's Forest Hill Collegiate Institute and completing his university education at University of Toronto, Sherman often worked for his uncle Louis Lloyd Winter, at his Empire Laboratories, the largest Canadian wholly owned pharmaceutical company at that time.
Split into simpler sentences: While at Toronto's Forest Hill Collegiate Institute and completing his university education at University of Toronto, Sherman often worked for his uncle Louis Lloyd Winter, at his pharmaceutical company, Empire Laboratories. Empire was the largest Canadian wholly owned pharmaceutical company at that time.