THE Reverend Leon Sullivan, the civil rights crusader who wrote the Sullivan Principles, an international code of business conduct that helped end apartheid in South Africa, has died of leukemia. He was 78. Sullivan, a former Philadelphia minister described the principals as “a code that companies of America and the world came to follow to end apartheid peacefully, starting with the workplace.” Companies doing business in South Africa were encouraged to give opportunities to their black workers and help local communities.