Hamaguchi Masashi, Tomida Naoki, Iyama Yuji
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
J Org Chem. 2007 Feb 16;72(4):1326-34. doi: 10.1021/jo0621975.
Reactions of azodicarboxylates and nitrosobenzene derivatives with acyloxyketenes generated from dehydrochlorination of alpha-acyloxyarylacetyl chlorides were carried out to give triacylbenzamidine and N-arylimide derivatives, respectively, in good yields. The same compounds were obtained from the reaction with mesoionic 1,3-dioxolium-4-olates generated by Rh2(OAc)4-catalyzed decomposition of aryldiazoacetic anhydride derivatives. Formation of the same compounds from the different starting materials indicates that their reactions involve the same intermediates. The formation of triacylbenzamidine and N-arylimide derivatives is explained by 1,3-dipolar cycloaddition between electron-deficient N=N or N=O bonds and mesoionic 1,3-dioxolium-4-olates following by decarboxylation, ring opening of the resultant carbonyl ylides, and subsequent Mumm rearrangement of the corresponding imidates. The reaction with singlet oxygen composed of more electronegative atoms than N=N and N=O bonds also gave products arising from the singlet oxygen adducts with 1,3-dioxolium-4-olates. The generation of less stable mesoionic 1,3-dioxolium-4-olates from acyloxyketenes was also confirmed by isolation of furandicarboxylates on generation of acyloxyketenes from alpha-acyloxyarylacetyl chlorides in the presence of reactive dipolarophile dimethyl acetylenedicarboxylate.
使偶氮二甲酸酯和亚硝基苯衍生物与由α-酰氧基芳基乙酰氯脱氯化氢生成的酰氧基烯酮反应，分别以良好的产率得到三酰基苯脒和N-芳基酰亚胺衍生物。由芳基重氮乙酸酐衍生物经Rh2(OAc)4催化分解生成的介离子型1,3-二氧杂环戊烯-4-醇盐反应也得到相同的化合物。由不同起始原料得到相同的化合物表明它们的反应涉及相同的中间体。三酰基苯脒和N-芳基酰亚胺衍生物的形成可以通过缺电子的N=N或N=O键与介离子型1,3-二氧杂环戊烯-4-醇盐之间的1,3-偶极环加成反应来解释，随后进行脱羧、所得羰基叶立德的开环以及相应亚胺酯的后续Mumm重排。与由比N=N和N=O键具有更高电负性的原子组成的单线态氧反应也得到了由单线态氧与1,3-二氧杂环戊烯-4-醇盐的加合物产生的产物。在有活性亲偶极体二甲基乙炔二羧酸酯存在的情况下，由α-酰氧基芳基乙酰氯生成酰氧基烯酮时分离出呋喃二甲酸酯，这也证实了由酰氧基烯酮生成较不稳定的介离子型1,3-二氧杂环戊烯-4-醇盐。
