Unlocking σ-Type Cyclopropenium Cation Transfer Reactions by an Iodine(III)-Based Umpolung Strategy

Abstract

σ-Type cyclopropenium cations (CPCs), which are formally generated by removing one substituent on the alkene of cyclopropenes, represent promising intermediates for forging functionalized cyclopropenes. However, σ-type CPCs are challenging to access and their synthetic utility remains largely unexplored. Recently, we introduced electrophilic cyclopropenyl-gold(III) species as equivalents of σ-type CPCs, which can then react with terminal alkynes or vinylboronic acids to afford alkynyl- or alkenyl-cyclopropenes. The merging of redox gold catalysis and a new class of hypervalent iodine reagents—the cyclopropenyl benziodoxoles (CpBXs)—plays a central role in generating the σ-type CPC equivalents. With the same reagents, we have also developed a synergistic Au/Ag bimetallic catalytic cyclopropenyl cross-coupling system that enables 1,1′-bicyclopropenyl derivatives to be forged in an efficient and modular manner. Our strategy provides access to previously inaccessible, yet highly useful, functionalized cyclopropenes, thereby significantly advancing both cyclopropene and hypervalent iodine chemistry.

1 Introduction

2 Transferring σ-Type CPCs to Terminal Alkynes

3 Transferring σ-Type CPCs to Vinylboronic Acids

4 Transferring σ-Type CPCs to Terminal Cyclopropenes

5 Reaction Mechanism

6 Conclusions

Key words

cyclopropane - 1,1′-bicyclopropenyl - cross-coupling - gold catalysis - hypervalent iodine reagents

Publication History

Received: 20 January 2025

Accepted after revision: 07 February 2025

Accepted Manuscript online:
07 February 2025

Article published online:
26 March 2025

• References

• 1 Bach RD, Dmitrenko O. J. Am. Chem. Soc. 2004; 126: 4444
• 2 Breslow R. J. Am. Chem. Soc. 1957; 79: 5318
• 3 Breslow R. Chem. Rec. 2014; 14: 1174
• 4 Wilson RM, Lambert TH. Acc. Chem. Res. 2022; 55: 3057
• 5 Yan Y, Vogt DB, Vaid TP, Sigman MS, Sanford MS. Angew. Chem. Int. Ed. 2021; 60: 27039
• 6a Tu H.-F, Jeandin A, Suero MG. J. Am. Chem. Soc. 2022; 144: 16737
• 6b Smyrnov V, Waser J. Angew. Chem. Int. Ed. 2024; 63: e202404265
• 7a Baird MS, Hussain HH, Nethercott W. J. Chem. Soc., Perkin Trans. 1 1986; 1845
• 7b Baird MS, Nethercott W. Tetrahedron Lett. 1983; 24: 605
• 8 Zhang Z.-Q, Zheng M.-M, Xue X.-S, Marek I, Zhang F.-G, Ma J.-A. Angew. Chem. Int. Ed. 2019; 58: 18191
• 9a Xu W, Chen Q.-Y. J. Org. Chem. 2002; 67: 9421
• 9b Cheng Z.-L, Chen Q.-Y. J. Fluorine Chem. 2005; 126: 39
• 10 Yoshimura A, Zhdankin VV. Chem. Rev. 2016; 116: 3328
• 11 Hari DP, Caramenti P, Waser J. Acc. Chem. Res. 2018; 51: 3212
• 12 Li X, Wodrich MD, Waser J. Nat. Chem. 2024; 16: 901
• 13 Talele TT. J. Med. Chem. 2020; 63: 5625
• 14 Yang Y, Antoni P, Zimmer M, Sekine K, Mulks FF, Hu L, Zhang L, Rudolph M, Rominger F, Hashmi AS. K. Angew. Chem. Int. Ed. 2019; 58: 5129
• 15 Briones JF, Davies HM. L. J. Am. Chem. Soc. 2012; 134: 11916
• 16a Gutman I, Potgieter JH. J. Chem. Educ. 1994; 71: 222
• 16b de Meijere A, Kozhushkov SI, Schill H. Chem. Rev. 2006; 106: 4926
• 17 Garratt PJ, Tsotinis A. J. Org. Chem. 1990; 55: 84
• 18 Grüger F, Szeimies G. Tetrahedron Lett. 1986; 27: 1563
• 19 Li X, Waser J. J. Am. Chem. Soc. 2024; 146: 29712