A new pathway for the ringexpansion reaction of antiaromaticboroles with organic azides is reported. While the reaction usually leads to 1,2‐azaborinines, it was diverted to the formation of a 1,2,3‐diazaborinine by changing the electronic characteristics of the reagents. The isolable azo‐azaborinine intermediate initially formed from the reaction of 1‐(2,3,4,5‐tetraphenylborolyl)ferrocene with 4‐azido‐N
Time to B radical: One‐electron reduction of 1‐ferrocenyl‐2,3,4,5‐tetraphenylborole results in a radical anion with 5 π electrons in the borole ring. Both EPR spectroscopicinvestigations and spin density calculations confirm the formation of a borol radical (see picture). Further reduction stimulates an intramolecular [(C5H5)Fe] migration from the cyclopentadienyl anion to the borole dianion.
B自由基的时间:1-二茂铁基2,3,4,5-四苯基硼原子的一次电子还原导致在硼原子环中具有5个π电子的自由基阴离子。EPR光谱研究和自旋密度计算都证实了硼自由基的形成(参见图片)。进一步还原会刺激分子内的[(C 5 H 5)Fe]从环戊二烯基阴离子迁移至硼酸二阴离子。