Norbornadiene-Fused Heterocycles: Synthesis and Bromination Reaction of 5,8-Dihydro-5,8-methanoquinoxaline Derivatives
作者:Tomoshige Kobayashi、Kiyomi Miki
DOI:10.1246/bcsj.71.1443
日期:1998.6
A norbornadiene-fused pyrazine was prepared by the condensation reaction of bicyclo[2.2.1]hept-5-ene-2,3-dione with ethylenediamine followed by oxidation. Treatments of the norbornadiene-fused pyrazine and its benzo derivative with bromine in carbon tetrachloride or in dioxane afforded trans-adducts as major products, accompanied by the formations of cis-adducts and dibromo derivatives derived from Wagner–Meerwein type skeletal rearrangement, while bromination of a fused dicyanopyrazine in carbon tetrachloride gave only a trans-adduct. In contrast, a fused pyrazine with an electron-donating N-oxide group gave a 7,9-dibromo derivative as the main component. The possibility of the intervention of a 2H-pyrazinium ion for the formation of the skeletally rearranged products is discussed together with the results of ab-initio (3-21G*) calculations.
双环[2.2.1]庚-5-烯-2,3-二酮与乙二胺发生缩合反应并氧化,制备出一种降冰片二烯融合吡嗪。在四氯化碳或二噁烷中用溴处理降冰片二烯融合吡嗪及其苯并呋喃衍生物时,主要产物为反式加合物,同时形成顺式加合物和由瓦格纳-梅尔韦恩型骨架重排衍生的二溴衍生物,而在四氯化碳中溴化融合二氰基吡嗪时,只产生反式加合物。与此相反,带有一个供电子的 N-氧化基团的融合吡嗪的主要成分是一种 7,9-二溴衍生物。本文结合非原位(3-21G*)计算的结果,讨论了 2H 吡嗪离子参与形成骨架重排产物的可能性。