Fritz Haber und Clara Immerwahr. Lernen aus der Geschichte

This contribution about Fritz Haber (1868–1934) and his wife Clara Immerwahr (1870–1915) shows us not only the changeful life of these two personalities which began their life full of hope and finished it then in tragedy. Their time is embedded into the history about the break‐up and then come‐down by the First World War of the first period of the German Empire, and also points out exemplarily science and industry of this time.     

Janus carbosilane/phosphorhydrazone dendrimers synthesized by the ‘click’ Staudinger reaction

The first association of carbosilane dendrons (having a phosphine at the focal point) with phosphorhydrazone dendrons (having a thiophosphoryl azide at the focal point) has been successfully carried out by ‘Staudinger click’ reaction. The corresponding Janus dendrimers possess the characteristics of both components; they are oily as the carbosilane dendrons, and they can be easily functionalized as the phosphorhydrazone dendrons.     

Der lange Weg zum Makromolekül

At about 1920 Hermann Staudinger coined the term macromolecule. It is based on Berzelius' term polymeric and has a long history, including Grahams' colloids and Naegelis micelles. Finally, in the 1930 the theses of Staudinger on size and structure of macromolecules were generally accepted and macromolecular chemistry is since that time the basis of the industry of plastics and rubber.     

无痕施陶丁格连接反应机理的理论研究

叠氮化合物和膦硫酯的无痕施陶丁格连接反应是一种有效生成酰胺键的方法. 通过密度泛函方法研究了无痕施陶丁格连接的反应机理. 计算结果表明反应的决速步为反应的第一步, 即膦进攻叠氮的端基氮, 形成膦基叠氮化物的过程. 膦亚胺中间体形成之后, 向不同方向转化(酰基迁移后水解或者直接水解)的难易程度决定了最终产物的组成. 对几种不同偶联试剂介导的无痕施陶丁格连接反应的计算结果, 都与实验数据相吻合.     

Synthesis of 3-oxo-1,4-diazepine-5-carboxamides and 6-(4-oxo-chromen-3-yl)-pyrazinones via sequential Ugi 4CC/Staudinger/intramolecular nucleophilic cyclization and Ugi 4CC/Staudinger/aza-Wittig reactions

An efficient approach for the assembly of 1,4-diazepine-based and 6-(4-oxo-chromen-3-yl)-pyrazinone-based frameworks has been developed that involves the Ugi four-component reaction (U-4CR) followed by Staudinger/nucleophilic cyclization and Staudinger/Aza-Wittig reactions, respectively. This convergent approach exhibits a high bond-forming efficiency, involving the use of readily available commercial reagents and is an example of the reconciliation of structural complexity with operational simplicity in a time- and cost-effective manner.     

Staudinger – Reaktionen am Bornanylen(dimethylphosphino)methylimin. Phosphorylierung des dabei gebildeten Trimethylsilylphosphinimids mit Diorganochlorphosphinen: unerwartete Bildung von Verbindungen mit P=N–P–P-Einheiten

Staudinger Reactions with Bornanylene(dimethylphosphino)methylimine. Phosphorylation of the Trimethylsilylphosphine Imide formed with Diorganochlorophosphines: unexpected Formation of Compounds with P=N–P–P Units Phosphinimido derivatives of the chiral bornanylene(dimethylphosphino)methyl imine have been obtained from its reactions with trimethylsilyl-, phenyl- and 4-nitrobenzoyl azide. A single crystal X-ray structure determination has been conducted on the 4-nitro-benzoylphosphinimido derivative of bornanylene(dimethylphosphino)methyl imine. The compound was found to crystallize with two independent molecules in the chiral monoclinic space group P2₁. The trimethylsilylphosphinimido derivative of bornanylene(dimethylphosphino)methyl imine was allowed to react with diorgano-chlorophosphines, with unexpected formation of compounds with PP-bonded RR′₂P=N–P⁽⁺⁾R″₂–PR″₂ groups. The ³¹P-NMR spectra of two representative compounds are simulated and discussed.     

Ortho-Phosphinoarenesulfonamide-Mediated Staudinger Reduction of Aryl and Alkyl Azides

Conventional Staudinger reductions of organic azides are sluggish with aryl or bulky aliphatic azides. In addition, Staudinger reduction usually requires a large excess of water to promote the decomposition of the aza-ylide intermediate into phosphine oxide and amine products. To overcome the challenges above, we designed a novel triaryl phosphine reagent 2c with an ortho-SO₂NH₂ substituent. Herein, we report that such phosphine reagents are able to mediate the Staudinger reduction of both aryl and alkyl azides in either anhydrous or wet solvents. Good to excellent yields were obtained in all cases (even at a diluted concentration of 0.01 M). The formation of B-TAP, a cyclic aza-ylide, instead of phosphine oxide, eliminates the requirement of water in the Staudinger reduction. In addition, computational studies disclose that the intramolecular protonation of the aza-ylide by the ortho-SO₂NH₂ group is kinetically favorable and responsible for the acceleration of Staudinger reduction of the aryl azides.     

Heteroatom effect on potential energy topology. A novel reaction mechanism of stereospecific Staudinger synthesis

The Staudinger synthesis of various β-carbolines and thienopyridines with acetyl chloride derivatives led to novel β-lactam-type fused heterocyclic compounds. The reaction was stereospecific, giving exclusively the cis cycloadducts as racemates. The enthalpy profile and the driving force for the cis-selectivity of this cycloaddition was studied by high level quantum chemical calculations and was assigned to a new effect of the neighbouring heteroatom of the acyl group. In the course of the reaction a new side product was formed supporting the mechanistic results.