Tetrathiafulvalene-Inserted Diphenoquinone: Synthesis,Structure, and Dynamic Redox Property

A new tetrathiafulvalene (TTF) derivative is synthesized, which is substituted with two phenoxy radicals on one 1,3-dithiole ring, and may have either open-shell diradical or closed-shell extended-quinoidal ground states. X-ray single crystal analysis and NMR measurements prove that this molecule has a closed-shell extended quinoidal structure both in the solid state and in solution. DFT calculations show the donor–acceptor electronic properties of this molecule with a well-separated HOMO–LUMO distribution and a small HOMO–LUMO energy gap. Because of this donor–acceptor character, this molecule gives both the dication and the dianion species by electrochemical oxidation and reduction. Furthermore, during the redox process between the neutral and dication states, this molecule exhibits unique changes in the cyclic voltammogram upon repeating the cycles or varying the scan rate. The observed electrochemical behavior is explained by the conformational changes in the electrochemically generated species, thus indicating that this molecule is classified as a dynamic redox system.     

Highly Efficient Multiple-Labeling Probes for the Visualization of Enzyme Activities

Quinone methide (QM) as a latent trapping unit has been widely explored in activity-based self-immobilizing reagents. However, further application of this strategy has been largely hampered by the limited labeling efficiency to proteins. In this study, a thorough investigation on the labeling efficiency and the structure of QM-based trapping unit is presented, from which a QM with multiple leaving groups was identified as an optimal trapping unit. An alkaline phosphatase (ALP) immobilizing reagent featured with this multiple-labeling trapping unit exhibited lower nonspecific binding and, remarkably, a significantly higher labeling efficiency over other immobilizing reagents upon enzymatic activation. The utility of this imaging reagent was further demonstrated with the in vitro and in vivo visualization of the ALP activities. Furthermore, the multiple functional trapping unit may find greater value in the other activity-based immobilizing probes.     

Concise Biosynthesis of Phenylfuropyridones in Fungi

Phenylfuropyridone natural products from fungi exhibit a range of antibacterial and cytotoxicity activities, and can potentiate azole antifungal compounds. We elucidated the biosynthetic pathway of compounds in the citridone family through heterologous reconstitution of the pfp pathway. We demonstrate that multiple members of this family can be accessed from a reactive ortho-quinone methide (o-QM) intermediate through electrocyclization, cycloisomerization, or conjugate addition. Formation of the quaternary carbon center in citridone B is catalyzed by an epoxide-forming P450 enzyme, followed by carbon skeletal rearrangement. Our results showcase how nature harvests the reactivities of an o-QM intermediate to biosynthesize complex natural products.     

3-亚甲基苯并吡喃-2,4-二酮与烯醇硅醚的Diels-Alder反应合成3,4- 二氢-2H,5H-吡喃并[3,2-c][1]苯并吡喃-5-酮衍生物

通过4-羟基香豆素与苯甲醛、甲醛和戊醛缩合产生的quinone methide与烯醇硅醚的Diels-Alder反应, 以较高产率合成了一系列含有硅氧基的3,4-二氢-2H,5H-吡喃并[3,2-c][1]苯并吡喃-5-酮衍生物. 用X射线单晶衍射确定了其中5个化合物的空间构型. 利用密度泛函(DFT)方法计算反应物之间的前线分子轨道相互作用, 对反应的区域选择性进行了研究, 计算结果与实验值相符.     

New Access to Sesquiterpene Hydroquinones: Synthesis of (+)‐ent‐Chromazonarol

A facile access to optically active (+)‐ent‐chromazonarol ent‐1, isolated from the sponge Disidea pallescens, is reported from commercially available (+)‐manool 4.     

Facile synthetic route to benzo[c]chromenones and thieno[2,3-c]chromenones

Convenient two-step procedure for the synthesis of fused chromenone derivatives was developed. Reduction of the obtained in the Meerwein arylation reaction aryl- and thienylquinones allowed to construct 6H-benzo[c]chromene-6-ones and 4H-thieno[2,3-c]chromen-4-one in a more cost- and time-effective manner in comparison with already known methods. The obtained products have provided a new entry to chromenone derivatives.     

异噁唑啉酮的不对称芳基化反应

在手性磷酸的作用下,实现了异噁唑啉酮和对苯醌单亚胺的不对称芳基化反应,以高收率和高对映选择性构建了4-芳基异噁唑啉酮衍生物。对其中一个产物进行单晶培养,确定了绝对构型。      

Synthesis of Pterocarpan-Type Heterocycles via Oxidative Cycloadditions of Phenols and Electron-Rich Arenes

Oxidation of 4-alkoxyphenols or 4-methoxynaphthol with phenyl iodonium(bis)trifluoroacetate (PIFA) in the presence of electron rich 2H-chromenes or dihydronaphthalenes affords pterocarpans or 5-carbapterocarpans via a formal [3 + 2] cycloaddition process. Acid-catalyzed ionization of quinone dimethylmonoacetal in the presence of 7-methoxy-2H-chromene gave similar results, suggesting a phenoxonium ion intermediate in the oxidative process.