TY - JOUR
T1 - Allylic Amination of Pd(II)-Allyl Complexes via High-Valent Pd Intermediates
AU - Wang, Yung Ching
AU - Rath, Nigam P.
AU - Mirica, Liviu M.
N1 - Funding Information:
The authors thank the Department of Energy’s BES Catalysis Science Program (DE-SC0006862) for financial support of the initial studies, and the authors also wish to thank the National Science Foundation (CHE-2102544) for financial support of the subsequent reactivity and EPR studies.
Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/8/8
Y1 - 2022/8/8
N2 - Organometallic high-valent Pd(allyl) complexes have been recently proposed to act as intermediates in catalytic allylic functionalization reactions. While a few PdIV(η1-allyl) complexes have been isolated and characterized, PdIII(η3-allyl) or PdIII(η1-allyl) complexes have not been detected or isolated to date. Reported herein is the synthesis, characterization, and reactivity of a series of PdII(η3-allyl) complexes supported by the tetradentate pyridinophane ligands N,N′-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane (tBuN4) and N,N′-di-tert-methyl-2,11-diaza[3.3](2,6)pyridinophane (MeN4). These PdII(η3-allyl) complexes exhibit accessible oxidation potentials and upon oxidation generate PdIII(allyl) complexes that were characterized by electron paramagnetic resonance (EPR) spectroscopy. Interestingly, the [(MeN4)PdIII(η3-allyl)]2+ complex undergoes a rearrangement to the [(MeN4)PdIII(η1-allyl)]2+ species at low temperatures. Moreover, fast allylic amination occurred within 15 min at room temperature upon the reaction of [(MeN4)PdII(η3-allyl)]+ complexes with N-fluorobenzenesulfonimide (NFSI), and the C-N bond formation step is proposed to occur at the Pd(IV) oxidation state, likely via a PdIV(η1-allyl) intermediate.
AB - Organometallic high-valent Pd(allyl) complexes have been recently proposed to act as intermediates in catalytic allylic functionalization reactions. While a few PdIV(η1-allyl) complexes have been isolated and characterized, PdIII(η3-allyl) or PdIII(η1-allyl) complexes have not been detected or isolated to date. Reported herein is the synthesis, characterization, and reactivity of a series of PdII(η3-allyl) complexes supported by the tetradentate pyridinophane ligands N,N′-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane (tBuN4) and N,N′-di-tert-methyl-2,11-diaza[3.3](2,6)pyridinophane (MeN4). These PdII(η3-allyl) complexes exhibit accessible oxidation potentials and upon oxidation generate PdIII(allyl) complexes that were characterized by electron paramagnetic resonance (EPR) spectroscopy. Interestingly, the [(MeN4)PdIII(η3-allyl)]2+ complex undergoes a rearrangement to the [(MeN4)PdIII(η1-allyl)]2+ species at low temperatures. Moreover, fast allylic amination occurred within 15 min at room temperature upon the reaction of [(MeN4)PdII(η3-allyl)]+ complexes with N-fluorobenzenesulfonimide (NFSI), and the C-N bond formation step is proposed to occur at the Pd(IV) oxidation state, likely via a PdIV(η1-allyl) intermediate.
UR - http://www.scopus.com/inward/record.url?scp=85135205562&partnerID=8YFLogxK
U2 - 10.1021/acs.organomet.2c00215
DO - 10.1021/acs.organomet.2c00215
M3 - Article
AN - SCOPUS:85135205562
SN - 0276-7333
VL - 41
SP - 2067
EP - 2076
JO - Organometallics
JF - Organometallics
IS - 15
ER -