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2‐Aminoalkylgold Complexes: The Putative Intermediate in Au‐Catalyzed Hydroamination of Alkenes Does Not Protodemetalate
Author(s) -
Gubler Joël,
Radić Mitar,
Stöferle Yannick,
Chen Peter
Publication year - 2022
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202200332
Subject(s) - hydroamination , protonation , cationic polymerization , chemistry , alkene , catalysis , reactivity (psychology) , electrophile , transition state , alkylation , amine gas treating , styrene , catalytic cycle , medicinal chemistry , photochemistry , polymer chemistry , organic chemistry , medicine , ion , polymer , alternative medicine , pathology , copolymer
Abstract Au‐catalyzed hydroamination proceeds well for alkynes but not alkenes. We report gas‐phase binding energies of alkenes and alkynes to a cationic Au center, which indicate that differences in binding are not the origin of the disparate chemical behavior. We further report the synthesis and characterization of 2‐aminoalkylgold complexes, which would be the intermediates in a hypothetical Au‐catalyzed hydroamination of styrene. The reactivity of the well‐characterized and isolable complexes reveals that protonation or alkylation of the 2‐aminoalkylgold complexes results in amine elimination in solution, and in the gas phase, indicating that the failure of Au‐catalyzed alkene hydroamination derives from a non‐competitive protodeauration step. We analyze possible transition states for the protodeauration, and identify an insufficiently strong Au‐proton interaction as the reason that the transition states lie too high in energy to compete.