試題詳解

15. Which sequence correctly ranks the following dienes in order of increasing reactivity in the Diels-Alder reaction? 
(A) 3 < 2 < 1
(B) 2 < 3 < 1
(C) 2 < 1 < 3
(D) 1 < 3 < 2
(E) 1 < 2 < 3 .