3′,5′-Dimethoxybenzoin esters are important photoremovable protecting groups which form 2-phenylbenzofuran derivatives upon photo-release. We utilized a similar concept to test a photochemical method of installing a benzofuran moiety to the conjugated backbone by subjecting O-acetylated (3′,5′-dimethylphenyl)heteroaryl acyloin derivatives through direct photo irradiation and a photo-induced electron transfer reaction. These photochemical methods were explored for a variety of heteroaromatic substrates appended on the ketone part of the O-acetylated cross-acyloin derivatives. The furan, thiophene and bithiophene derivatives led to the expected cyclized (benzofuran capped) products but the derivatives with extended conjugation decomposed under direct irradiation. However, under irradiation in the presence of an electron donor such as triethylamine, the extended acyloin derivatives afforded both cyclized and deacetoxylated products. The semiconducting nature of the extended cyclized products was also explored and tested for solution-processed organic field effect transistors, providing a maximum hole mobility of 1.3 × 10⁻⁶ cm² V⁻¹ s⁻¹.

中文翻译：

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在直接辐射和光诱导电子转移条件下 ，O-乙酰化的（3'，5'-二甲氧基苯基）杂芳基酰基蛋氨酸衍生物的调制光化学反应性†

3′，5′-二甲氧基苯偶姻酯是重要的可光除去的保护基，其在光释放时形成2-苯基苯并呋喃衍生物。我们利用相似的概念来测试通过直接光照射和光诱导的电子转移反应使O-乙酰化的（3'，5'-二甲基苯基）杂芳基酰基蛋氨酸衍生物经受将苯并呋喃部分安装到共轭骨架上的光化学方法。对这些光化学方法进行了探索，以发现附着在O酮部分上的各种杂芳族底物-乙酰化的交叉酰基辅酶衍生物。呋喃，噻吩和联噻吩衍生物可产生预期的环化（苯并呋喃封端）产品，但在直接辐射下具有扩展共轭作用的衍生物会分解。然而，在电子给体例如三乙胺存在下的辐射下，扩展的酰基辅酶衍生物既提供环化的产物又提供脱乙酰氧基化的产物。对于溶液处理的有机场效应晶体管，还探索并测试了扩展的环化产物的半导体性质，该晶体管的最大空穴迁移率为1.3×10 ^-6 cm ² V ^-1 s ^-1。