system e.g. 18a (n= 3 or 4), the 2-benzopyran-3-ones 10a, 10b and 10c undergo endo-selective intramolecular Diels–Alder addition of the connecting chain to give cis-BC fused ring systems of type 13. The adduct 13b is converted into the ester 21 with methanolic HCl and into the ketol 36 by LiAlH4 reduction followed by oxidation (MnO2). The ketone 31 is prepared from 21 by epoxidation followed by BF3·Et2O-catalysed
与在二烯体系的末端之间缺少桥键的邻
喹啉甲烷(例如18a(n = 3或4))不同,2-苯并
吡喃-3-酮10a,10b和10c经历了内链选择性分子内Diels-Alder加成连接链的过程得到13型的顺式-BC稠合环系统。加合物13b用HCl的
甲醇溶液转化成酯21,并通过LiAlH 4还原然后氧化(MnO 2)转化成酮醇36 。酮31由21进行环氧化,然后由BF 3 ·Et 2 O催化重排制备;使用NaOMe-CD 3 OD时,它无法顺式-反式异构化,并且由于C-6质子的酸度过高,未能在C-8处引入
氘。由21获得的顺式-二氢
萘26得到带有KOBu t-(CD 3)2 SO的顺式-27,在这种情况下显示出更大的顺式稠合环体系的热力学稳定性。