Synthesis of 1,2-annulated and 1,2-unsubstituted pyrrolo[2,1,5-de]quinolizin-5-ones (cycl[3.3.2]azin-5-ones) via [3+2] cycloadditions of 1-oxoquinolizinium ylides with cyclic alkenes
作者:Yun Liu、Hua-You Hu、Yan Zhang、Hong-Wen Hu、Jian-Hua Xu
DOI:10.1039/c0ob00299b
日期:——
1,2-Annulated pyrrolo[2,1,5-de]quinolizin-5-ones (cycl[3.3.2]azin-5-ones) 6a–6k, 8a–8b and 9 have been synthesized by one pot tandem reactions of 2-acetyl-N-phenacylpyridinium bromides (1a–1d) with electron-deficient cyclic alkenes (N-alkyl(aryl)maleimides, benzoquinones and naphthoquinone) in the presence of sodium carbonate as a base and tetrakispyridinecobalt(II) dichromate (TPCD) as an oxidant. These products are formed by 1.3-dipolar cycloaddition of the 1-oxoquinolizinium ylides generated in situ from 1a–1d with the alkene followed by dehydrogenation of the primary cycloadduct under the action of TPCD. Similar reactions of the ylides generated in situ from 1a–1f with maleic anhydride gave the 1,2-unsubstituted pyrrolo[2,1,5-de]quinolizin-5-ones 7a–7f via oxidative bisdecarboxylation and dehydrogenation of the primary cycloadducts under the action of TPCD.
1,2-环状吡咯[2,1,5-de]喹啉-5-酮(cycl[3.3.2]azin-5-酮)6a–6k,8a–8b和9是通过将2-乙酰基-N-苯甲酰吡啶溴化物(1a–1d)与电子缺乏的环烯烃(N-烷基(芳基)马来酰亚胺、苯醌和萘醌)在碳酸钠作为碱和四氮化钴(II)二铬酸盐(TPCD)作为氧化剂的存在下进行一锅串联反应合成的。这些产品是通过与烯烃的1-氧喹啉鎓盐烯基的1.3-偶极环加成反应在原位生成,并随后在TPCD作用下对初级环加成物进行脱氢得到的。用1a–1f在原位生成的烯基与马来酸酐的类似反应通过在TPCD作用下的氧化双脱羧化和初级环加成物的脱氢反应生成了1,2-无取代的吡咯[2,1,5-de]喹啉-5-酮7a–7f。