2,3,4,6‐Tetrahydro‐1,6‐dithia[3‐a]azaphenalene (THDTAP) is a heteropolycycle possessing two reactive sites for acylation. The regioselective acylation of THDTAP was achieved at the para and meta positions with respect to the nitrogen atom under conditions of AlCl₃ (1.3 equiv, 25 °C) and AlCl₃ (4 equiv, 40 °C), respectively. A series of para‐ and meta‐benzophenones having a donor–acceptor‐type structure were then synthesized, in which the THDTAP and benzoyl moieties serve as donor and acceptor, respectively. Under typical McMurry reaction conditions, para‐ and meta‐benzophenones show different reactivity, and the electronic nature of the aryl group also plays a pivotal role. Theoretical, electrochemical, and photophysical studies indicate that the electronic structures of para‐ and meta‐benzophenones are distinct because the electronic communication between donor and acceptor subunits are different for the two regioisomers. The para‐benzophenones show off/on fluorescence upon acidification/neutralization and hence might be useful as chemosensors.

中文翻译：

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2,3,4,6-四氢-1,6-二硫[3-a]氮杂苯二酚对供体-受体型二苯甲酮的区域选择性酰化作用

2,3,4,6-四氢-1,6-二硫杂[3- a ]氮杂萘（THDTAP）是一个杂多环，具有两个酰化反应位点。在AlCl ₃（1.3当量，25°C）和AlCl ₃（4当量，40°C）的条件下，分别在相对于氮原子的对位和间位实现了THDTAP的区域选​​择性酰化。然后合成了一系列具有供体-受体型结构的对-和间-二苯甲酮，其中THDTAP和苯甲酰基部分分别充当了供体和受体。在典型的McMurry反应条件下，对位和间位‐二苯甲酮显示出不同的反应性，芳基的电子性质也起着关键作用。理论，电化学和光物理研究表明，对位和间位二苯甲酮的电子结构是不同的，因为两种区域异构体的供体和受体亚基之间的电子通讯是不同的。的对位-benzophenones炫耀/上在酸化时/中和荧光，因此可能是作为化学传感器是有用的。