Modification for synthetic purposes on the diels-alder adducts 56 and 62 has only rarely been considered . 为了达到合成的目的，对Diels-Alder加成物（56）和（62）加以改造的问题很少有人考虑。
2.
Modification for synthetic purposes on the diels - alder adducts 56 and 62 has only rarely been considered 为了达到合成的目的，对diels - alder加成物（ 56 ）和（ 62 ）加以改造的问题很少有人考虑。
