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Published September 26, 2018 | Supplemental Material + Accepted Version
Journal Article Open

Oxidative Coupling with Zr(IV) Supported by a Noninnocent Anthracene-Based Ligand: Application to the Catalytic Cotrimerization of Alkynes and Nitriles to Pyrimidines

Abstract

We report the synthesis and reactivity of Zr complexes supported by a 9,10-anthracenediyl-linked bisphenoxide ligand, L. Zr^(IV)LBn_2 (1) undergoes facile photolytic reduction with concomitant formation of bibenzyl and Zr^(IV)L(THF)_3 (2), which displays a two-electron reduced anthracene moiety. Leveraging ligand-stored reducing equivalents, 2 promotes the oxidative coupling of internal and terminal alkynes to isolable zirconacyclopentadiene complexes, demonstrating the reversible utilization of anthracene as a redox reservoir. With diphenylacetylene under CO, cyclopentadienone is formed stoichiometrically. 2 is competent for the catalytic formation of pyrimidines from alkynes and nitriles. Mechanistic studies suggest that selectivity for pyrimidine originates from preferred formation of an azazirconacyclopentadiene intermediate, which reacts preferentially with nitriles over alkynes.

Additional Information

© 2018 American Chemical Society. Received: July 13, 2018. Published: August 28, 2018. We are grateful to the Dreyfus Foundation (T.A.), the Agency of Science, Technology and Research (A*STaR), Singapore (C.H.L.), and the Caltech's SURF (J.N.R.) and WAVE (M.A.L.) programs for funding. We thank Lawrence M. Henling, and Michael K. Takase for crystallographic assistance, and David VanderVelde for advice on NMR. The NSF (CRIF:MU CHE0639094) and NIH (RR027690) are thanked for instrument grants to Caltech. The authors declare no competing financial interest.

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Accepted Version - nihms-1583473.pdf

Supplemental Material - ja8b07418_si_001.cif

Supplemental Material - ja8b07418_si_002.pdf

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August 19, 2023
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