Jürgen Sauer, the first professor of chemistry at the University of Regensburg, is scientifically known for his significant insights into the Diels-Alder reaction and for journeys into the realm of shortlived intermediates.
Jürgen Sauer was born on June 11, 1931 in Halle (Saale) as the son of the economist Dr. Hans Sauer and his wife Thea. His mother went blind, which taught the children to take on responsibility at an early age. His outstanding Abitur grade of 1.0 (1950) earned Jürgen Sauer a scholarship from the Bavarian Fund for Highly Gifted, which allowed him to study chemistry at the Ludwig-Maximilians-Universität (LMU) München.
His doctoral thesis, the work on which was carried out in the laboratories of the author, dealt with "Nucleophilic Substitutions via Arynes"; the discovery that liberation of arynes (dehydroaromatics) from ArHal with lithium piperidide is more rapid than with the more basic phenyllithium [1] is still practiced today. In postdoctoral studies, he contributed to the total synthesis of chlorophyll with Robert B. Woodward (who was legendary even then) at Harvard University; the use of a thioaldehyde group allowed him to achieve an important step in the synthesis.
Back in Munich, Sauer chose "Kinetics and Mechanism of the Diels-Alder Reaction" for his Habilitation topic. Maleic anhydride acted as standard for comparing the rate constants of 1,3dienes, while the reactivity of the dienophiles was determined versus cyclopentadiene and 9,10-dimethylanthracene. [2] Tetracyanoethylene (TCNE) and 1,2,4-triazoline-3,5-diones were several orders of magnitude faster than maleic anhydride.
In 1968, Sauer was called as professor and dean of science (1968-1970) to the newly founded University of Regensburg. The arrival of further colleagues meant that the planning of construction and teaching was spread over more shoulders. The first chemistry students were taught in a provisional building in 1972, and in 1975 the new laboratories were ready. The second organic chemist at Regensburg (1971), Gottfried Märkl, had gained experience in Würzburg. The book "Integriertes Organisches Praktikum" by S. Hünig, G. Märkl, and J. Sauer, was published in 1979.
The reaction of electron-rich 1,3-dienes with electron-poor dienophiles corresponds to the "Alder rule". In 1962, Sauer developed the counterpart, the "Diels-Alder reaction with inverse electron requirement", that is, the formation of sixmembered rings from electron-poor 1,3-dienes with electron-rich dienophiles. [3] Here, 1,2,4,5-tetrazine-3,6-dicarboxylic acid ester acted as the standard diene, and for the activity of the dienophiles the