Isolation and characterization of diazoolefins

ABSTRACT Diazoolefins tend to be highly reactive compounds that rapidly lose dinitrogen. So far, most experimental evidence for diazoolefins is indirect, via trapping experiments. Here we

show that diazoolefins are observed to form in reactions of N-heterocyclic olefins with nitrous oxide. The products benefit from resonance stabilization, which enables isolation on a

preparative scale, and comprehensive characterization, which includes crystallographic analyses. N-heterocyclic diazoolefins show a strong ylidic character, with a high charge density at the

carbon atom next to the diazo group. Despite the presence of terminal N2 groups, N-heterocyclic diazoolefins display a good thermal stability, which surpasses that observed for most

diazoalkanes. N-heterocyclic diazoolefins can bind transition and main group metal complexes without the liberation of dinitrogen, and spectroscopic data show that they are strong electron

donors. They can also undergo reactions that involve the N2 group, as evidenced by cycloaddition reactions. Access through your institution Buy or subscribe This is a preview of subscription

content, access via your institution ACCESS OPTIONS Access through your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access

subscription $29.99 / 30 days cancel any time Learn more Subscribe to this journal Receive 12 print issues and online access $259.00 per year only $21.58 per issue Learn more Buy this

article * Purchase on SpringerLink * Instant access to full article PDF Buy now Prices may be subject to local taxes which are calculated during checkout ADDITIONAL ACCESS OPTIONS: * Log in

* Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS ISOLATION AND REACTIVITY OF AN ELUSIVE DIAZOALKENE Article 29

April 2021 ELECTROCHEMICAL OXIDATIVE DIFUNCTIONALIZATION OF DIAZO COMPOUNDS WITH TWO DIFFERENT NUCLEOPHILES Article Open access 17 March 2023 SYNTHETIC APPROACHES TO 1,4-DICARBONYL COMPOUNDS

Article 07 November 2022 DATA AVAILABILITY Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under

deposition numbers 2059964 (1), 2059969 (3), 2081293 (4), 2084389 (7), 2059970 (8), 2059965 (9), 2059966 (10), 2059971 (11), 2059972 (12), 2082844 (13), 2059967 (14), 2059973 (15), 2059968

(16) and 2059974 (17). Copies of the data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/. Relevant data for this study are available within the article and its

Supplementary Information. Original data files for the spectroscopic analyses can be obtained from the authors upon reasonable request. REFERENCES * Regitz, M. & Maas, G. _Diazo

Compounds_ (Academic, 1986). * Ford, A. et al. Modern organic synthesis with α-diazocarbonyl compounds. _Chem. Rev._ 115, 9981–10080 (2015). Article  CAS  PubMed  Google Scholar  * Candeias,

N. R., Paterna, R. & Gois, P. M. P. Homologation reaction of ketones with diazo compounds. _Chem. Rev._ 116, 2937–2981 (2016). Article  CAS  PubMed  Google Scholar  * Doyle, M. P.,

Duffy, R., Ratnikov, M. & Zhou, L. Catalytic carbene insertion into C–H bonds. _Chem. Rev._ 110, 704–724 (2010). Article  CAS  PubMed  Google Scholar  * Green, S. P. et al. Thermal

stability and explosive hazard assessment of diazo compounds and diazo transfer reagents. _Org. Process Res. Dev._ 24, 67–84 (2020). Article  CAS  PubMed  Google Scholar  * Hock, K. J. &

Koenigs, R. M. The generation of diazo compounds in continuous-flow. _Chem. Eur. J._ 24, 10571–10583 (2018). Article  CAS  PubMed  Google Scholar  * Knorr, R. Alkylidenecarbenes,

alkylidenecarbenoids, and competing species: which Is responsible for vinylic nucleophilic substitution, [1 + 2] cycloadditions, 1.5-CH insertions, and the Fritsch–Buttenberg–Wiechell

rearrangement? _Chem. Rev._ 104, 3795–3849 (2004). Article  CAS  PubMed  Google Scholar  * Kirmse, W. Alkenylidenes in organic synthesis. _Angew. Chem. Int. Ed. Engl._ 36, 1164–1170 (1997).

Article  CAS  Google Scholar  * Lahi, P. M. & Berson, J. A. Thermal rearrangement of an allenic diazoalkane and intermolecular capture of a diazoethene by a cyclopropene to give a common

dihydropyridazine product. _J. Am. Chem. Soc._ 103, 7011–7012 (1981). Article  Google Scholar  * Ando, W., Furuhata, T. & Takata, T. A highly efficient reaction of thiobenzophenone for

1-diazoalkene. _Tetrahedron Lett._ 26, 4499–4500 (1985). Article  CAS  Google Scholar  * Munschauer, R. & Maas, G. 1,3-(C→O) silyl shift in α-diazo α-silyl ketones: cycloaddition

reactions and kinetic proof for the β-siloxydiazoalkane intermediate. _Angew. Chem. Int. Ed. Engl._ 30, 306–308 (1991). Article  Google Scholar  * Munschauer, R. & Maas, G. Cycloaddition

products from (1-diazo-2-oxoalkyl)silanes and cyclopropenes. A silatropic 2,3-diazabicyclo[3.1.0]hex-3-ene/1,4-dihydropyidazine equilibrium. _Chem. Ber._ 125, 1227–1234 (1992). Article  CAS

  Google Scholar  * Manz, B. & Maas, G. Synthesis of 5-alkylidene-4,5-dihydro-3_H_-1,2,4(λ3)-diazaphospholes from α-silyl-α-diazoketones and phosphaalkenes. _Tetrahedron_ 52, 10053–10072

(1996). Article  CAS  Google Scholar  * Brahms, J. C. & Dailey, W. P. Difluoropropadienone as a source of difluorovinylidene and difluorodiazoethene. _J. Am. Chem. Soc._ 112, 4046–4047

(1990). Article  CAS  Google Scholar  * Bott, K. 2,2-(_N_,_N_′-dimethyl-ethylendiamino)-ethylenediazonium-ion, ein diazonium ion mit ungewöhnlichen eigenschaften. _Tetrahedron Lett._ 26,

3199–3202 (1985). Article  CAS  Google Scholar  * Bott, K. Dialkylamino-substituierte ethylendiazoniumsalze. _Chem. Ber._ 120, 1867–1871 (1987). Article  CAS  Google Scholar  * Klein, S.,

Tonner, R. & Frenking, G. Carbodicarbenes and related divalent carbon(0) compounds. _Chem. Eur. J._ 16, 10160–10170 (2010). Article  CAS  PubMed  Google Scholar  * Fustier-Bouitignon,

M., Nebra, N. & Mézailles, N. Geminal dianions stabilized by main group elements. _Chem. Rev._ 119, 8555–8700 (2019). Article  CAS  Google Scholar  * Frenking, G. & Tonner, R.

Carbodicarbenes–divalent carbon(0) compounds exhibiting carbon–carbon donor–acceptor bonds. _WIREs Comput. Mol. Sci._ 1, 869–878 (2011). Article  CAS  Google Scholar  * Antoni, P. W., Golz,

C., Holstein, J. J., Pantazis, D. & Hansmann, M. M. Isolation and reactivity of an elusive diazoalkene. _Nat. Chem._ 13, 587–593 (2021). Article  CAS  PubMed  Google Scholar  * Roy, M.

M. D. & Rivard, E. Pushing chemical boundaries with N-heterocyclic olefins (NHOs): from catalysis to main group element chemistry. _Acc. Chem. Res._ 50, 2017–2025 (2017). Article  CAS 

PubMed  Google Scholar  * Crocker, R. D. & Nguyen, T. V. The resurgence of the highly ylidic N-heterocyclic olefins as a new class of organocatalysts. _Chem. Eur. J._ 22, 2208–2213

(2016). Article  CAS  PubMed  Google Scholar  * Naumann, S. Synthesis, properties & applications of N-heterocyclic olefins in catalysis. _Chem. Commun._ 55, 11658–11670 (2019). Article 

CAS  Google Scholar  * Severin, K. Synthetic chemistry with nitrous oxide. _Chem. Soc. Rev._ 44, 6375–6386 (2015). Article  CAS  PubMed  Google Scholar  * Eymann, L. Y. M. et al. Synthesis

of organic super-electron-donors by reaction of nitrous oxide with N-heterocyclic olefins. _J. Am. Chem. Soc._ 141, 17112–17116 (2019). Article  CAS  PubMed  Google Scholar  * Allen, F. H.

Bond lengths relationships in diazo and diazonium compounds. _Acta Cryst. B_ 51, 378–381 (1995). Article  Google Scholar  * Al-Rafia, S. M. I. et al. Intercepting low oxidation sate main

group hydrides with a nucleophilic N-heterocyclic olefin. _Chem. Commun._ 47, 6987–6989 (2011). Article  CAS  Google Scholar  * Gruber, M., Bauer, W., Maid, H., Schöll, K. & Tykwinski,

R. R. Synthetic and NMR studies on hexaphenylcarbodiphosphorane (Ph3P=C=PPh3). _Inorg. Chim. Acta_ 468, 152–158 (2017). Article  CAS  Google Scholar  * Frisch, M. et al. Gaussian 16,

Revision A.03 (Gaussian, Inc., 2016). * Petz, W. Addition compounds between carbones, CL2, and main group Lewis acids: a new glance at old and new compounds. _Coord. Chem. Rev._ 291, 1–27

(2015). Article  CAS  Google Scholar  * Zhao, L., Chai, C., Petz, W. & Frenking, G. Carbones and carbon atom as ligands in transition metal complexes. _Molecules_ 25, 4943 (2020).

Article  CAS  PubMed Central  Google Scholar  * Wiberg, K. B. Application of the Pople–Santry–Segal CNDO method to the cyclopropylcarbinyl and cyclobutyl cation and to bicyclobutane.

_Tetrahedron_ 24, 1083–1096 (1968). Article  CAS  Google Scholar  * Glendening, E. D. & Weinhold, F. Natural resonance theory: II. Natural bond order and valency. _J. Comput. Chem._ 19,

610–627 (1998). Article  CAS  Google Scholar  * Glendening, E. D. & Weinhold, F. Natural resonance theory: I. General formalism. _J. Comput. Chem._ 19, 593–609 (1998). Article  CAS 

Google Scholar  * Glendening, E. D., Badenhoop, J. & Weinhold, F. Natural resonance theory: III. Chemical applications. _J. Comput. Chem._ 19, 628–646 (1998). Article  CAS  Google

Scholar  * Yang, Z., Stivanin, M. L., Jurberg, I. D. & Koenigs, R. M. Visible light-promoted reactions with diazo compounds: a mild and practical strategy towards free carbene

intermediates. _Chem. Soc. Rev._ 49, 6833–6847 (2020). Article  CAS  PubMed  Google Scholar  * Tskhovrebov, A. G., Vuichoud, B., Solari, E., Scopelliti, R. & Severin, K. Adducts of

nitrous oxide and N-heterocyclic carbenes: syntheses, structures, and reactivity. _J. Am. Chem. Soc._ 135, 9486–9492 (2013). Article  CAS  PubMed  Google Scholar  * Eymann, L. Y. M.,

Scopelliti, R., Tirani, F. F. & Severin, K. Synthesis of azo dyes from mesoionic carbenes and nitrous oxide. _Chem. Eur. J._ 24, 7957–7963 (2018). Article  CAS  PubMed  Google Scholar  *

Liu, S.-k, Shih, W.-C., Chen, W.-C. & Ong, T.-G. Carbodicarbenes and their captodative behavior in catalysis. _ChemCatChem_ 10, 1483–1498 (2018). Article  CAS  Google Scholar  * Dyker,

C. A., Lavallo, V., Donnadieu, B. & Bertrand, G. Synthesis of an extremely bent acyclic allene (a ‘carbodicarbene’): a strong donor ligand. _Angew. Chem. Int. Ed._ 47, 3206–3209 (2008).

Article  CAS  Google Scholar  * Chen, W.-C., Hsu, Y.-C., Lee, C.-Y., Yap, G. P. A. & Ong, T.-G. Synthetic modification of acyclic bent allenes (carbodicarbenes) and further studies on

their structural implications and reactivities. _Organometallics_ 32, 2435–2442 (2013). Article  CAS  Google Scholar  * Chen, W.-C. et al. Expanding the ligand framework diversity of

carbodicarbenes and direct detection of boron activation in the methylation of amines with CO2. _Angew. Chem. Int. Ed._ 54, 15207–15212 (2015). Article  CAS  Google Scholar  * Chen, W.-C. et

al. The elusive three-coordinate dicationic hydrido boron complex. _J. Am. Chem. Soc._ 136, 914–917 (2014). Article  CAS  PubMed  Google Scholar  * Dröge, T. & Glorius, F. The measure

of all rings—N-heterocyclic carbenes. _Angew. Chem. Int. Ed._ 49, 6940–6952 (2010). Article  CAS  Google Scholar  Download references ACKNOWLEDGEMENTS This work was supported by funding from

the EPFL. We thank A. Gitlina for the infrared spectroscopy measurements, W. Feuerstein for help with the synthesis of 1, C. Berton for help with NMR analyses and D. Ortiz for help with

mass spectrometry. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland Paul

Varava, Zhaowen Dong, Rosario Scopelliti, Farzaneh Fadaei-Tirani & Kay Severin Authors * Paul Varava View author publications You can also search for this author inPubMed Google Scholar

* Zhaowen Dong View author publications You can also search for this author inPubMed Google Scholar * Rosario Scopelliti View author publications You can also search for this author inPubMed

 Google Scholar * Farzaneh Fadaei-Tirani View author publications You can also search for this author inPubMed Google Scholar * Kay Severin View author publications You can also search for

this author inPubMed Google Scholar CONTRIBUTIONS P.V. and K.S. designed the experiments, P.V. performed the synthetic experiments and analysed the data, Z.D. performed the computational

analysis, R.S. and F.F.-T. collected and processed the X-ray data, and P.V., Z.D. and K.S. co-wrote the manuscript. All the authors discussed the results and commented on the manuscript.

CORRESPONDING AUTHOR Correspondence to Kay Severin. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. ADDITIONAL INFORMATION PEER REVIEW INFORMATION _Nature

Chemistry_ thanks Gabriela Borosky, Tiow-Gan Ong and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. PUBLISHER’S NOTE Springer Nature remains

neutral with regard to jurisdictional claims in published maps and institutional affiliations. SUPPLEMENTARY INFORMATION SUPPLEMENTARY INFORMATION Experimental procedures, analytical data

including copies of NMR spectra, and details regarding the crystallographic and computational analyses. SUPPLEMENTARY DATA 1 Crystallographic data for compound 1; CCDC reference 2059964.

SUPPLEMENTARY DATA 2 Crystallographic data for compound 3; CCDC reference 2059969. SUPPLEMENTARY DATA 3 Crystallographic data for compound 4; CCDC reference 2081293. SUPPLEMENTARY DATA 4

Crystallographic data for compound 7; CCDC reference 2084389. SUPPLEMENTARY DATA 5 Crystallographic data for compound 8; CCDC reference 2059970. SUPPLEMENTARY DATA 6 Crystallographic data

for compound 9; CCDC reference 2059965. SUPPLEMENTARY DATA 7 Crystallographic data for compound 10; CCDC reference 2059966. SUPPLEMENTARY DATA 8 Crystallographic data for compound 11; CCDC

reference 2059971. SUPPLEMENTARY DATA 9 Crystallographic data for compound 12; CCDC reference 2059972. SUPPLEMENTARY DATA 10 Crystallographic data for compound 13; CCDC reference 2082844.

SUPPLEMENTARY DATA 11 Crystallographic data for compound 14; CCDC reference 2059967. SUPPLEMENTARY DATA 12 Crystallographic data for compound 15; CCDC reference 2059973. SUPPLEMENTARY DATA

13 Crystallographic data for compound 16; CCDC reference 2059968. SUPPLEMENTARY DATA 14 Crystallographic data for compound 17; CCDC reference 2059974. RIGHTS AND PERMISSIONS Reprints and

permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Varava, P., Dong, Z., Scopelliti, R. _et al._ Isolation and characterization of diazoolefins. _Nat. Chem._ 13, 1055–1060 (2021).

https://doi.org/10.1038/s41557-021-00790-3 Download citation * Received: 09 February 2021 * Accepted: 17 August 2021 * Published: 07 October 2021 * Issue Date: November 2021 * DOI:

https://doi.org/10.1038/s41557-021-00790-3 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this content: Get shareable link Sorry, a shareable link is not

currently available for this article. Copy to clipboard Provided by the Springer Nature SharedIt content-sharing initiative