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Gold(I) Complexes with Eight‐Membered NHC Ligands: Synthesis, Structures and Catalytic Activity
Author(s) -
CervantesReyes Alejandro,
Rominger Frank,
Rudolph Matthias,
Hashmi A. Stephen K.
Publication year - 2020
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.202000281
Subject(s) - cycloisomerization , chemistry , catalysis , ligand (biochemistry) , propargyl , phenol , selectivity , spectroscopy , stereochemistry , medicinal chemistry , crystallography , organic chemistry , receptor , biochemistry , physics , quantum mechanics
A series of expanded‐ring NHC gold complexes of the formula (NaphtDHD−Ar)Au−X (NaphtDHD=4,5‐dihydro‐1 H ‐naphtho[1,8‐ ef ][1,3]diazocin‐3(2 H )‐ylidene; Ar: Mes=2,4,6‐trimethylphenyl, Dipp=2,6‐diisopropylphenyl or Xyl=2,6‐dimethylphenyl; X=Cl, NCCH 3 , NTf 2 ) have been synthesized, including the first gold(I) triflimidate complex ( 5 ) stabilized by an eight‐membered NHC ligand. The new organogold compounds have been characterized by mass spectrometry, IR spectroscopy, and 1 H and 13 C NMR spectroscopy. The structural geometries of 3 b – c and 5 have been unequivocally established by crystallographic analysis revealing broad N‐C‐N angles (>121°) and high buried volume values (46–54%). The first catalytic studies were carried out on the cycloisomerization of 1,6‐enynes, obtaining full conversions (0.5 mol% catalyst loading) and excellent endo / exo selectivity (up to 99:1), and on the gold‐catalyzed phenol synthesis. Lastly, the (NaphtDHD‐Dipp)Au + NTf 2 − species was subjected to a kinetic experiment in the cyclization of a N ‐propargyl carboxamide to evaluate the efficiency of the pre‐formed catalyst ( 5 ) and the in situ activated gold complex ( 3 b +AgNTf 2 ).