A Twenty-Year Survey in Low-Valent Cobalt-Catalyzed Transformations Comes to an End – A Farewell

Abstract

In this Account, I report the start of my independent career, concerning cobalt-catalyzed carbon–carbon bond formations and the twenty-year long journey to the final decision to abandon the field. Some highlights, such as the regiodiverse neutral Diels–Alder reaction and the cobalt versus ruthenium-catalyzed Alder-ene reaction are discussed. Besides such highlights, also some aspects that led to unpleasant experiences are reported from a personal point of view.

1 Introduction

2 The Regiodivergent Neutral-Diels–Alder Reaction

3 The Chemoselective [2+2+2] Cyclotrimerization of Alkynes and Nitriles

4 The Cobalt-Catalyzed Alder-ene Reaction

5 The Isomerization of Carbon–Carbon Double Bonds

6 The Final Chord

7 Conclusion

Key words

Alder-ene reaction - catalysis - cobalt - cyclotrimerization - Diels–Alder reaction - hydrovinylation - isomerization

Publication History

Received: 18 October 2022

Accepted after revision: 27 October 2022

Article published online:
23 November 2022

• References

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Shortly after I started my independent career in Munich in September 1999, my PhD advisor Prof. Eberhard Steckhan passed away so-to-say in the lecture hall in early 2000 and, under shock, we submitted our first paper on cobalt catalysis as soon as possible to a formerly high-ranked journal, see:
• 3a Hilt G, du Mesnil F.-X. Tetrahedron Lett. 2000; 41: 6757

But, I made the same mistake again, see:
• 3b Hilt G, Korn TJ. Tetrahedron Lett. 2001; 42: 2783
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For early reports, see:
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• 7 For the synthesis of the moenocinol side-chain, see: Hilt G, Treutwein J. Chem. Commun. 2009; 1395
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• 17 For the synthesis of credneramides, see: Erver F, Hilt G. J. Org. Chem. 2012; 77: 5215
• 18 For the synthesis of urushiol, see: Schmidt A, Hilt G. Chem. Asian J. 2014; 9: 2407
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• 20 For the correction of reference 19, see: Pünner F, Schmidt A, Hilt G. Angew. Chem. Int. Ed. 2019; 58: 17103
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• 22 For eternity unpublished results
• 23 Surprisingly, a Web of Science search for Prof. Donald Hilvert in association with the key word ‘cobalt’ gave not a single hit?!
• 24 Over the process of preparing this Account, I had a brief discourse with the editor-in-charge and he sent me a very useful comment for many situations in life. Prof. K. Peter C. Vollhardt wrote in German: ‘Schwamm drüber!’, which translates most likely into: ‘No hard feelings!’ The German metaphor is much more illustrative.