Regiospecifically Fluorinated Polycyclic Aromatic Hydrocarbons via Julia–Kocienski Olefination and Oxidative Photocyclization. Effect of Fluorine Atom Substitution on Molecular Shape,The Journal of Organic Chemistry

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Regiospecifically Fluorinated Polycyclic Aromatic Hydrocarbons via Julia–Kocienski Olefination and Oxidative Photocyclization. Effect of Fluorine Atom Substitution on Molecular Shape
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2016-03-22 00:00:00 , DOI: 10.1021/acs.joc.5b02580
Shaibal Banerjee ₁ , Saikat Sinha ₁ , Padmanava Pradhan ₁ , Alessio Caruso ₂ , Daniel Liebowitz ₂ , Damon Parrish ₃ , Miriam Rossi ₂ , Barbara Zajc _{1,

4}

Affiliation

A modular synthesis of regiospecifically fluorinated polycyclic aromatic hydrocarbons (PAHs) is described. 1,2-Diarylfluoroalkenes, synthesized via Julia–Kocienski olefination (70–99% yields), were converted to isomeric 5- and 6-fluorobenzo[c]phenanthrene, 5-and 6-fluorochrysene, and 9- and 10-benzo[g]chrysene (66–83% yields) by oxidative photocyclization. Photocyclization to 6-fluorochrysene proceeded more slowly than conversion of 1-styrylnaphthalene to chrysene. Higher fluoroalkene dilution led to a more rapid cyclization. Therefore, photocyclizations were performed at higher dilutions. To evaluate the effect of fluorine atom on molecular shapes, X-ray data for 5- and 6-fluorobenzo[c]phenanthrene, 6-fluorochrysene, 9- and 10-fluorobenzo[g]chrysene, and unfluorinated chrysene as well as benzo[g]chrysene were obtained and compared. The fluorine atom caused a small deviation from planarity in the chrysene series and decreased nonplanarity in the benzo[c]phenanthrene derivatives, but its influence was most pronounced in the benzo[g]chrysene series. A remarkable flattening of the molecule was observed in 9-fluorobenzo[g]chrysene, where the short 2.055 Å interatomic distance between bay-region F-9 and H-8, downfield shift of H-8, and a 26.1 Hz coupling between F-9 and C-8 indicate a possible F-9···H-8 hydrogen bond. In addition, in 9-fluorobenzo[g]chrysene, the stacking distance is short at 3.365 Å and there is an additional interaction between the C-11–H and C-10a of a nearby molecule that is almost perpendicular.

中文翻译：

通过 Julia-Kocienski 烯化和氧化光环化制备区域特异性氟化多环芳烃。氟原子取代对分子形状的影响

描述了区域特异性氟化多环芳烃 (PAH) 的模块化合成。通过 Julia-Kocienski 烯化合成的 1,2-二芳基氟烯烃（产率 70-99%）被转化为异构体 5- 和 6-氟苯并[ c ]菲、5-和 6-氟苯以及 9- 和 10-苯并[ g ]chrysene（66-83％产率）通过氧化光环化。光环化为 6-氟比 1-苯乙烯基萘转化为进行得更慢。氟代烯烃稀释度越高，环化速度越快。因此，光环化在更高的稀释度下进行。为了评估氟原子对分子形状的影响，使用了 5-和 6-氟苯并[ c ]菲、6-氟苯并[ g ]、未氟化以及苯并[g]的 X 射线数据。 g ]chrysene 得到并比较。氟原子导致了系列中平面性的微小偏差，并降低了苯并[ c ]菲衍生物中的非平面性，但其影响在苯并[ g ]系列中最为明显。在 9-氟苯并[ g ]chrysene 中观察到分子的显着扁平化，其中湾区 F-9 和 H-8 之间的短 2.055 Å 原子间距离、H-8 的低场位移以及 F 之间的 26.1 Hz 耦合-9和C-8表示可能的F-9…H-8氢键。此外，在 9-氟苯并[ g ]chrysene 中，堆积距离很短，为 3.365 Å，并且附近分子的 C-11–H 和 C-10a 之间几乎垂直，存在额外的相互作用。

更新日期：2016-03-22

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