Direct light activation of hypervalent iodine reagents: substrate- controlled C-C or C-H alkynylation of cyclopropanes Vu-Trung-Tin Nguyen, Jerome Waser LCSO, EPFL, Switzerland The use of the ring strain of cyclopropanes is well-established to enable C-C bond cleavage. More reactive Donor-Acceptor systems have been intensively investigated. 1 Less reactive Donor-only arylcyclopropanes could also be functionalized through oxidative activation. 2 Our group recently reported aryl-substituted EBX reagents for the oxidative functionalization of several molecules under direct visible light irradiation. 3 We wondered if this approach could also be applied for alkynylation of arylcyclopropanes.
Herein, we report the direct light activation of ethnylbenziodoxolone (EBX) reagents for the oxyalkynylation of aryl- and amino-cyclopropanes as well as styrenes. Irradiation with visible light at 440 nm promoted the reaction without the need for a photocatalyst. By the choice of the aryl group on the cyclopropane, it was possible to completely switch the outcome of the reaction from the oxyalkynylation of the C-C bond to the alkynylation of the C-H bond.This effect has been speculatively attributed to the conformational control induced by the aryl group on the cyclopropane ring. 4 References 1. F. Schneider, J. Kaschel and D. B. Werz, Angew. Chem., Int. Ed. , 2014, 53 , 5504.Selected examples: ( a ) O. Ilchenko, M. Hedberg and K. J. Szabó, Chem. Sci. , 2017, 8 , 1056. ( b ) S. M. Banik, K. M. Mennie and E. N. Jacobsen, J. Am. Chem. Soc. , 2017, 139 , 9152. ( c ) M. H. Gieuw, Z. H. Ke and Y. Y. Yeung, Angew. Chem., Int. Ed. , 2018, 57 , 3782 ( d ) S. Yang, L. Wang, H. Zhang, C. Liu, L. Zhang, X. Wang, G. Zhang, Y. Li and Q. Zhang, ACS Catal. , 2019, 9 , 716. (e) H. Liu, Y. Li, D. X. Wang, M. M. Sun, and C. Feng, Org. Lett. , 2020, 22 , 8681 2. G. E. Amos,D. Cavalli, F. Le Vaillant and J. Waser, Angew. Chem., Int. Ed. , 2021, 60 , 23827. 3. V. T. Nguyen and J. Waser, ChemRxiv , 2022
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