Christensen Christian A, Bryce Martin R, Batsanov Andrei S, Becher Jan
Department of Chemistry, University of Durham, Durham, UK DH1 3LE.
Org Biomol Chem. 2003 Feb 7;1(3):511-22. doi: 10.1039/b211153p.
A range of new functionalised 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene (TTFAQ) derivatives have been synthesised from the key di(halomethyl) building blocks, 10-[4,5-bis(bromomethyl)-1,3-dithiol-2-ylidene]-anthracene-9(10H)-one 10, 10-[4,5-bis(chloromethyl)-1,3-dithiol-2-ylidene]anthracene-9(10H)-one 11 and 9-[4,5-bis(chloromethyl)-1,3-dithiol-2-ylidene]-10-[4,5-bis(hexylsulfanyl)- 1,3-dithiol-2-ylidene]-9,10-dihydroanthracene 18. A Diels-Alder strategy comprising trapping of the transient exocyclic diene 19, which is derived from 18, with 1,4-naphthoquinone leads to the aromatised TTFAQ anthraquinone system 21. Horner-Wadsworth-Emmons olefination of 21 with the anion generated from reagent 22 gave the fused bis(TTFAQ) structure 23. Pyrrolo-annelated derivatives 30-34 have been obtained in a sequence of reactions from compound 10. Mono-formylation of the pyrrole ring of 32 and 33 under Vilsmeier conditions gave 35 and 36 which upon reaction with 2,4,5,7-tetranitrofluorene gave the donor-pi-acceptor diads 38 and 39. Cyclic voltammetry (CV) in solution for all the TTFAQ derivatives shows the typical quasi-reversible two-electron oxidation wave of the TTFAQ core at potentials which vary slightly depending on the substituents. For example, the value of Eox is raised by the electron withdrawing anthraquinone and tetranitrofluorene units of 21 and 38, respectively. The CV of the conjugated TTFAQ dimer 23 showed two, two-electron oxidation waves corresponding to the sequential formation of 23(2+) and 23(4+) (delta Eox = 130 mV) providing evidence for a significant intramolecular electronic interaction, i.e. the dication 23(2+) acts as a conjugated donor-pi-acceptor diad, thereby raising the oxidation potential of its partner TTFAQ unit. Spectroelectrochemical studies on 23 support this explanation. A strong intramolecular charge transfer band at lambda max 538 nm is seen in the UV-Vis spectra of the TTFAQ-pi-tetranitrofluorene diads 38 and 39. The X-ray crystal structures are reported for compounds 30, 33 and 34. The pyrrolo-TTFAQ moiety adopts a saddle-shape with the central ring of the dihydroanthracene moiety folded along the C(9) ... C(10) vector in each case. Significant intermolecular interactions are observed in the structures.
一系列新型功能化的9,10 - 双（1,3 - 二硫醇 - 2 - 亚基）-9,10 - 二氢蒽（TTFAQ）衍生物已由关键的二（卤甲基）结构单元合成，即10 - [4,5 - 双（溴甲基）-1,3 - 二硫醇 - 2 - 亚基] - 蒽 - 9(10H) - 酮10、10 - [4,5 - 双（氯甲基）-1,3 - 二硫醇 - 2 - 亚基]蒽 - 9(10H) - 酮11和9 - [4,5 - 双（氯甲基）-1,3 - 二硫醇 - 2 - 亚基] - 10 - [4,5 - 双（己基硫烷基）-1,3 - 二硫醇 - 2 - 亚基] - 9,10 - 二氢蒽18。一种狄尔斯 - 阿尔德策略，包括用1,4 - 萘醌捕获由18衍生出的瞬态环外二烯19，得到芳构化的TTFAQ蒽醌体系21。21与由试剂22产生的阴离子进行霍纳 - 沃兹沃思 - 埃蒙斯烯化反应，得到稠合双（TTFAQ）结构23。吡咯并稠合衍生物30 - 34通过一系列反应从化合物10获得。在维尔施迈尔条件下，32和33的吡咯环进行单甲酰化反应得到35和36，它们与2,4,5,7 - 四硝基芴反应得到供体 - π - 受体二联体38和39。所有TTFAQ衍生物在溶液中的循环伏安法（CV）表明，TTFAQ核心具有典型的准可逆双电子氧化波，其电位根据取代基略有变化。例如，21和38的吸电子蒽醌和四硝基芴单元分别提高了Eox的值。共轭TTFAQ二聚体23的CV显示出两个双电子氧化波，对应于23(2+)和23(4+)的顺序形成（ΔEox = 130 mV），这为显著的分子内电子相互作用提供了证据，即双阳离子23(2+)作为共轭供体 - π - 受体二联体，从而提高了其伙伴TTFAQ单元的氧化电位。对23的光谱电化学研究支持了这一解释。在TTFAQ - π - 四硝基芴二联体38和39的紫外 - 可见光谱中，在λmax 538 nm处观察到一个强的分子内电荷转移带。报道了化合物30、33和34的X射线晶体结构。在每种情况下，吡咯并 - TTFAQ部分呈鞍形，二氢蒽部分的中心环沿C(9)……C(10)向量折叠。在结构中观察到显著的分子间相互作用。
