Treatment of title triflate 1 with two equivalents of pyridine yields the  4-(4-phenyl-1,9a-dihydro-2H-quinolizin-2-ylidene)morpholinium triflate  (4). Similarly, quinoline and isoquinoline convert 1 into the benzodi-  hydroquinolizine salts 6 and 7, respectively. This novel access to the 1,9a-  dihydro-2H-quinolizine system is based on base-initiated cyclization of a  dicationic intermediate such as 4-(3-pyridiniopropenylidene)  morpholinium ditriflate 2. Tertiary amines catalyze the isomerization of 4  into the 3,4-dihydroquinolizinium triflate 8.
                                    用
吡啶的两个当量处理
三氟甲磺酸1,得到4-(4-苯基-1,9a-二氢-2H-喹嗪-2-亚基)吗啉
三氟甲磺酸盐(4)。同样,
喹啉和
异喹啉分别将1转化为苯并二氢喹嗪盐6和7。这种新颖的1,9a-二氢-2H-喹嗪系统是基于碱引发的双环化二元中间体,如4-(3-
吡啶基
丙烯亚基)吗啉二
三氟甲磺酸盐2。叔胺催化4异构化为3,4-二氢喹嗪
三氟甲磺酸盐8。