Tom Wirtanen
@vttresearch.com
Senior Scientist in Industrial Synthesis & Catalysis
VTT Technical Research Centre of Finland
RESEARCH, TEACHING, or OTHER INTERESTS
Organic Chemistry
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Soilikki Kotanen, Tom Wirtanen, Riitta Mahlberg, Adina Anghelescu‐Hakala, Tapani Harjunalanen, Pia Willberg‐Keyrilainen, Timo Laaksonen, and Essi Sarlin
Wiley
AbstractThree different cyclic carbonates (ethylene, propylene, and butylene carbonate) that can be derived from CO2 were successfully polymerized with hexamethylenediamine to form non‐isocyanate polyurethanes (NIPUs) via self‐polycondensation route without the use of harmful di‐isocyanates. Three different catalysts were compared for their performance in self‐polycondensation. Increasing the side chain length in cyclic carbonate increased the amount of urea side reaction and decreased the solubility of the final product. The increased amount of urea lead to a more thermoset behavior as the melting and decomposition took place simultaneously. Furthermore, the extent of urea side reaction and melting behavior were adjustable with the selection of the catalyst or polymerization parameters. With ethylene and propylene carbonate based precursors, it was possible to obtain promising melting temperatures and lap shear strength for the NIPUs when optimized polymerization parameters and catalyst were used.
Johannes Winter, Tobias Prenzel, Tom Wirtanen, Dieter Schollmeyer, and Siegfried R. Waldvogel
Wiley
AbstractThe use of electric current in synthetic organic chemistry offers a sustainable tool for the selective reductive synthesis of quinoline N‐oxides starting from easily accessible nitro compounds. The reported method employs mild and reagent‐free conditions, a simple undivided cell, and constant current electrolysis set‐up which provides conversion with a high atom economy. The synthesis of 30 differently substituted quinoline N‐oxides was successfully performed in up to 90 % yield. Using CV studies, the mechanism of the selective formation of the quinoline N‐oxides was elucidated. The technical relevance of the described reaction could be shown in a 50‐fold scale‐up reaction.
Valtteri Oksanen, Sari Rautiainen, and Tom Wirtanen
Wiley
AbstractBifuran motifs can be accessed with nickel‐bipyridine electrocatalyzed homocouplings of bromine‐substituted methyl furancarboxylates, which, in turn, can be prepared from hemicellulose‐derived furfural. The described protocol uses sustainable carbon‐based graphite electrodes in the simplest setup – an undivided cell with constant current electrolysis. The reported method avoids using a sacrificial anode by employing triethanolamine as an electron donor.
Anna Lenarda, Tom Wirtanen, and Juho Helaja
Georg Thieme Verlag KG
AbstractCarbocatalysis is a heterogeneous metal-free catalytic technique of high potential for current and future synthetic processes. Carbocatalysts entail heterogeneous materials based on sp2/sp3 interconnected carbons decorated with oxygen functional groups, defects, and other heteroatom dopants. In this short review, we cover a wide range of different carbocatalyzed oxidative dehydrogenation reactions, with particular emphasis on liquid-phase transformations that are relevant for synthetic organic chemists.1 Introduction2 Structures of Catalytic Carbon Materials3 Oxidative Aromatizations with Activated Carbon4 Oxidative Dehydrogenation CH–CH Couplings5 Oxidative Dehydrogenation Coupling of Benzyl Amines6 Oxidations of Alcohols7 Other Oxidative Transformations by Heteroatom-Doped Carbon Materials8 Asphaltene Oxide9 Conclusions and Outlook
Vladimir Iashin, Tom Wirtanen, and Jesus E. Perea-Buceta
MDPI AG
Nucleophilic ionic sources of fluoride are essential reagents in the synthetic toolbox to access high added-value fluorinated building blocks unattainable by other means. In this review, we provide a concise description and rationale of the outstanding features of one of these reagents, tetramethylammonium fluoride (TMAF), as well as disclosing the different methods for its preparation, and how its physicochemical properties and solvation effects in different solvents are intimately associated with its reactivity. Furthermore, herein we also comprehensively describe its historic and recent utilization, up to December 2021, in C-F bond-forming reactions with special emphasis on nucleophilic aromatic substitution fluorinations with a potential sustainable application in industrial settings, as well as its use as a base capable of rendering unprecedented transformations.
Tom Wirtanen, Tobias Prenzel, Jean-Philippe Tessonnier, and Siegfried R. Waldvogel
American Chemical Society (ACS)
The critical aspects of the corrosion of metal electrodes in cathodic reductions are covered. We discuss the involved mechanisms including alloying with alkali metals, cathodic etching in aqueous and aprotic media, and formation of metal hydrides and organometallics. Successful approaches that have been implemented to suppress cathodic corrosion are reviewed. We present several examples from electroorganic synthesis where the clever use of alloys instead of soft neat heavy metals and the application of protective cationic additives have allowed to successfully exploit these materials as cathodes. Because of the high overpotential for the hydrogen evolution reaction, such cathodes can contribute toward more sustainable green synthetic processes. The reported strategies expand the applications of organic electrosynthesis because a more negative regime is accessible within protic media and common metal poisons, e.g., sulfur-containing substrates, are compatible with these cathodes. The strongly diminished hydrogen evolution side reaction paves the way for more efficient reductive electroorganic conversions.
Lukas Enders, David S. Casadio, Santeri Aikonen, Anna Lenarda, Tom Wirtanen, Tao Hu, Sami Hietala, Lucília S. Ribeiro, Manuel Fernando R. Pereira, and Juho Helaja
Royal Society of Chemistry (RSC)
Air oxidized activated carbon offers a robust, efficient, metal-free and recyclable catalyst for aromatizations of N-heterocycles, O2 being the terminal oxidant.
Mikko K. Mäkelä, Evgeny Bulatov, Kiia Malinen, Juulia Talvitie, Martin Nieger, Michele Melchionna, Anna Lenarda, Tao Hu, Tom Wirtanen, and Juho Helaja
Wiley
AbstractOxidized active carbon (oAC) catalyses the formation of polysubstituted quinolines from o‐vinyl anilines and aldehydes. The reaction proceeds in a cascade manner through condensation, electrocyclization and dehydrogenation, and gives access to a wide range of quinolines with alkyl and/or aryl substituents as demonstrated with 40 examples. The metal‐free catalytic procedure allows a heterogeneous protocol for the synthesis of various polysubstituted quinolines. The mechanistic studies imply that both the acid and quinoidic groups in oAC are integral for the catalytic manifold.magnified image
David S. Casadio, Santeri Aikonen, Anna Lenarda, Martin Nieger, Tao Hu, Stefan Taubert, Dage Sundholm, Mikko Muuronen, Tom Wirtanen, and Juho Helaja
Wiley
Abstract Mildly thermal air or HNO3 oxidized activated carbons catalyse oxidative dehydrogenative couplings of benzo[b]fused heteroaryl 2,2’‐dimers, e.g., 2‐(benzofuran‐2‐yl)‐1H‐indole, to chiral 3,3’‐coupled cyclooctatetraenes or carbazole‐type migrative products under O2 atmosphere. DFT calculations show that the radical cation and the Scholl‐type arenium cation mechanisms lead to different products with 2‐(benzofuran‐2‐yl)‐1H‐indole, being in accord with experimental product distributions.
Tom Wirtanen, Eduardo Rodrigo, and Siegfried R. Waldvogel
Wiley
Tom Wirtanen, Eduardo Rodrigo, and Siegfried R. Waldvogel
Wiley
Invited for the cover of this issue is the group of Siegfried R. Waldvogel at Johannes Gutenberg-Universität Mainz. The image depicts the idea that synthetic electrochemistry is green chemistry in its essence. Read the full text of the article at 10.1002/chem.201905874.
Tom Wirtanen, Eduardo Rodrigo, and Siegfried R. Waldvogel
Wiley
Abstract Electrosynthesis of 2H‐2‐(aryl)benzo[d]‐1,2,3‐triazoles and their N‐oxides from 2‐nitroazobenzene derivatives is reported. The electrolysis is conducted in a very simple undivided cell under constant current conditions with a leaded bronze cathode and a glassy carbon anode. The product distribution between 2H‐2‐(aryl)benzo[d]‐1,2,3‐triazoles and their N‐oxides can be guided by simply controlling the current density and the amount of the charge applied. The reaction tolerates several sensitive functional groups in reductive electrochemistry. The usefulness and the applicability of the synthetic method is demonstrated by a formal synthesis of an antiviral compound.
Tom Wirtanen, Santeri Aikonen, Mikko Muuronen, Michele Melchionna, Marianna Kemell, Fatemeh Davodi, Tanja Kallio, Tao Hu, and Juho Helaja
Wiley
AbstractHNO3‐oxidized carbon nanotubes catalyze oxidative dehydrogenative (ODH) carbon–carbon bond formation between electron‐rich (hetero)aryls with O2 as a terminal oxidant. The recyclable carbocatalytic method provides a convenient and an operationally easy synthetic protocol for accessing various benzofused homodimers, biaryls, triphenylenes, and related benzofused heteroaryls that are highly useful frameworks for material chemistry applications. Carbonyls/quinones are the catalytically active site of the carbocatalyst as indicated by model compounds and titration experiments. Further investigations of the reaction mechanism with a combination of experimental and DFT methods support the competing nature of acid‐catalyzed and radical cationic ODHs, and indicate that both mechanisms operate with the current material.
Santeri Aikonen, Mikko Muuronen, Tom Wirtanen, Sami Heikkinen, Joshua Musgreave, Jordi Burés, and Juho Helaja
American Chemical Society (ACS)
The gold-catalyzed 1,3-O-transposition of ynones occurs intermolecularly via a cyclic organo-gold acetal intermediate formed from the nucleophilic oxo attack of a second ynone, i.e. either starting material or product, on a gold-activated ynone. The combination of 1H NMR monitored kinetic data, analyzed using variable time normalization analysis (VTNA) and kinetic modeling, and density functional theory (DFT) was used to elucidate the mechanism. A significant acceleration of the reaction rate could be achieved by the addition of a substoichiometric amount of electron-rich aldehyde as a mediator, allowing the gold-catalyzed 1,3-O-transposition of terminal ynones to ynaldehydes. The mechanism is further supported by NMR characterization of the acetal intermediate and 18O labeling experiments. A model for predicting the reactivity from aldehyde frontier molecular orbital energies is also presented.
Aleksandar R. Todorov, Tom Wirtanen, and Juho Helaja
American Chemical Society (ACS)
Facile photoreductive protocols have been developed to remove benzyl O-protective groups from oxyarene N-heterocycles at positions capable for 2-/4-O-pyridine-2-/4-pyridone tautomerism. Blue light irradiation, a [Ru] or [Ir] photocatalyst, and ascorbic acid in a water-acetonitrile solution debenzylates a variety of aryl N-heterocycles cleanly and selectively. Ascorbic acid has two functions in the reaction. On the one hand, it protonates the N-heterocycles that reduces their reduction potentials notably and on the other hand it acts as a sacrificial reductant. Reduction potentials and free energy barriers calculated at the CPCM-B3LYP/6-31+G** level can predict the reactivities of the studied substrates.
T. Wirtanen, M. Muuronen, J. Hurmalainen, H. M. Tuononen, M. Nieger, and J. Helaja
Royal Society of Chemistry (RSC)
A synthetic method applied to the synthesis of shandougenine B.
Tom Wirtanen, Mikko K. Mäkelä, Jawad Sarfraz, Petri Ihalainen, Sami Hietala, Michele Melchionna, and Juho Helaja
Wiley
Appropriate and fine-tuned treatments of amorphous carbon (AC) involving aqua regia or concentrated HNO3 lead to oxidised carbon materials (oAC) which are able to catalyse 2,2′- and 3,3′-homocouplings of various functionalised indoles with outstanding activity. This newly developed carbocatalysed CC bond formation can be achieved under mild thermal conditions. The study on the scope of the reaction revealed that the reaction can be extended to the homocoupling of other substrates of high synthetic interest such as 2-naphthol, 2-functionalised benzofurans and benzothiofurans. The characterisation of oAC with XPS together with ad hoc experiments aimed at blocking the active site revealed that the presence and distribution of CO functionalities is critical and correlates well with the catalytic activity. Such experiments provide solid support for elucidation of the mechanism, suggesting a quinone nature of the active CO groups, which are spontaneously regenerated by oxygen. This is confirmed by the fact that 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is able to promote the coupling in a stoichiometric fashion.
Tom Wirtanen, Mikko Muuronen, Michele Melchionna, Michael Patzschke, and Juho Helaja
American Chemical Society (ACS)
A synthetic approach for asymmetric ring-fused cyclopentadienes (Cps) with a chiral carbon at the ring junction has been established from chiral enynamines by achiral Au(III) catalysis. On the basis of experimental and theoretical data, the proposed mechanistic pathway from enynamines to Cps occurs via a Au(III) ene cis-trans isomerization step. Computational studies at DFT and NEVPT2 levels advocate that the cis-trans isomerization step proceeds via a dual Au(III) push-pull assisted intermediate with a low computed rotation barrier. The chirality transfer occurs through a helical-shaped transition state with allenic character. The scope of the catalysis encompasses sterically bulky enynamines including terpene natural products.
Jesus E. Perea-Buceta, Tom Wirtanen, Otto-Ville Laukkanen, Mikko K. Mäkelä, Martin Nieger, Michele Melchionna, Nina Huittinen, Jose A. Lopez-Sanchez, and Juho Helaja
Wiley
However, the reductive nature of those conditions limited thereaction scope and precluded the possibility of furthercascade functionalization. Soon after, Somorjai, Toste, andco-workers reported that Pt nanoparticles supported onmesoporous silica are able to efficiently promote the intra-molecular heterocyclization of N-carbamate protected 2-alkynylanilinestoaffordthecorrespondingindoleproductsinexcellent yields.