as soon as i took the medicine, my headache disappeared.

이 문장이 no sooner had i takenthe medicine than my headache disappeared.

이건 알겠는데 no sooner 을 문장속으로 다시 넣었을때

i had no sooner taken the medicine than my headache disappeared.
으로 바뀌는데 no sooner 위치가 왜 had taken 사이에 와야 하는지
문법적 근거를 알고 싶습니다.^^