A Homage to Siegfried Hünig and His Research

Abstract

Examples from different research areas of Siegfried Hünig are displayed to remind us that organic chemistry owes much more than Hünig's base to this exceptionally versatile and creative chemist. The main research lines dealing with the synthesis and physical characterization of new dyes, multistage redox systems, and organic metals will be presented as well as his contributions to enamine chemistry, the discovery of diimine as a hydrogenation agent, and nucleophilic acylation with trimethylsilyl cyanide, which are less well‐known nowadays. In addition, exotic compounds with parallel C=C and N=N bonds were systematically studied in Hünig's group. Reflecting on the development of his research demonstrates both the importance of a systematic approach and how fruitful entirely unexpected results are if they meet a “well‐prepared mind”. During Hünig's academic career, teaching played an indisputable role. His efforts in modernizing the chemistry institute at Würzburg and his support of young researchers in the academic system in Germany are also highlighted.

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

“…After 16 hours at room temperature and chromatographic purification compound 3 was isolated in 79% yield as colorless liquid. Interestingly, under similar conditions, but employing two equivalents of copper(I) iodide in the presence of Hünig’s base [ 55 ] in acetonitrile at 40 °C provided 4,4'-bis(1,2,3-triazole) 4 in low yield ( Scheme 2 , reaction 2). Performing this reaction at room temperature gave a mixture of 3 and 4 .…”

The Story of the Little Blue Box: A Tribute to Siegfried Hünig

“…What is not generally known, however, is that he also made a name [37] for himself in the field of organic metals and multistate redox systems in addition to the invention [38] of new methods and reagents for organic synthesis. In fact, in contrast with the only two publications [36] that are related to the study of sterically hindered tertiary amines, Hünig recorded [33] in more than 100 publications the systematic investigation of π-electron systems that harbor redox properties. Much of this research activity, which centered [39] on bipyridinium salts, was to have a major influence on our own development of the redox chemistry associated with the little blue box.…”

“…There is, however, a scientific giant [33] without whom this 35‐year odyssey of exploration would most likely not have occurred: this giant (Figure 1) was Professor Siegfried Hünig. As one of the most renowned organic chemists of the latter half of the 20th century, Hünig not only pioneered [34] the syntheses of viologen‐containing cyclophanes, but also spearheaded [35] the evolution of the rich redox chemistry, for example, π‐dimerization (pimerization), associated with viologen‐containing compounds.…”

Tf2O/TTBP (2,4,6-Tri-tert-butylpyrimidine): An Alternative Amide Activation System for the Direct Transformations of Both Tertiary and Secondary Amides

“…Non-ionic, non-nucleophilic bases play important roles in many organic reactions. The most well-known may be the Hünig base . Brown and Kanner’s base [2,6-di- tert -butylpyridine (DTBP, Figure , 1a )] and Stang and Anderson’s base [2,6-di- tert -butyl-4-methylpyridine (DTBMP, 1b )] also represent two very useful ones.…”