G. G. Lavoie et al.
tion were grown at À358C under nitrogen by slow liquid diffusion of pen-
tane into a saturated solution in THF. 1H NMR (400 MHz, C6D6): d=
6.87–6.82 (m, 3H; p-CH(2,6-xylyl) +m-CH(2,6-xylyl)), 6.65 (d, 3J=3.9 Hz, 2H;
m-CH(mesityl)), 6.00 (d, 3J=2.6 Hz, 1H; NCHCHN(mesityl)), 5.63 (s, 3J=
2.6 Hz, 1H; NCHCHN(mesityl)), 2.67 (brs, 3H; o-CH3(2,6-xylyl)), 2.03–1.99 (m,
9H; o-CH3(2,6-xylyl) +o-CH3(mesityl) +p-CH3(mesityl)), 1.61 (s, 3H; o-
CH3(mesityl)), 1.58 ppm (s, 9H; (CH3)3C); 13C NMR (100 MHz, CDCl3): d=
163.4 (NCN), 160.0 (C=N), 145.4 (i-C(2,6-xylyl)), 136.4 (o-C(mesityl)), 135.8 (o-
C(mesityl)), 133.6 (i-C(mesityl)), 129.3 (m-CH(mesityl)), 129.1 (m-C(mesityl)), 128.0
(m-CH(2,6-xylyl)), 123.7 (p-CH(2,6-xylyl)), 117.3 (NCCN(mesityl)), 115.0
age, over six times greater than those with 3. The perform-
ance of complex 9 was consistent with our initial experi-
ments with 2,6-dimethylaniline (Table 2, entries 2, 4 and 6),
with conversions lower than those of either 3 or 6, and reac-
tion rates intermediate between those of these two com-
plexes.
Conclusion
(NCCN(mesityl)), 41.7 (CACHTNUTRGNNEGU(CH3)3), 29.8 (CACHTUTGNERNN(NGU CH3)3), 20.9 (p-CH3(mesityl)), 19.5
(brs; o-CH3(2,6-xylyl)), 17.9 (o-CH3(mesityl)), 17.3 ppm (o-CH3(mesityl)); FTIR
(cast film): n˜C N =1660, n˜C=S =1204 cmÀ1; elemental analysis calcd (%)
=
A
series of imidazole-2-thione and imidazol-2-ylidene
for C25H31N3S: C 74.03, H 7.70, N 10.36; found: C 74.13, H 7.56, N 10.38.
gold(I) complexes have been prepared to evaluate the effect
of sulfur and of a pendent imine fragment on the hydroami-
nation of phenylacetylene with substituted anilines. All cata-
lysts tested were highly selective, with the exclusive forma-
tion of the Markovnikov addition product. In the imidazole-
2-thione catalyst systems 3 and 5, the presence of the imine
group was found to have a positive impact on the conver-
sion achieved by the catalyst. This enhancement was, howev-
er, not noted in the imidazol-2-ylidene series, in which the
conversion observed with [(C^IminetBu)AuCl] (6) was com-
parable to that of [(IMes)AuCl], albeit at a markedly superi-
or initial reaction rate. Complex 6 showed better perform-
ance than complex 3, with conversions consistently exceed-
ing 95% by using either sterically or electronically demand-
ing anilines. Overall, complex 6 delivers excellent overall
performance (rates, selectivity and scope of substrates) com-
pared to other known gold catalysts.[23,33]
{1-[(2,6-Dimethylphenylimino)-2,2-dimethylpropyl]-3-(2,4,6-trimethylphe-
nyl)imidazole-2-thione}gold chloride, [(S^IminetBu)AuCl] (3): Dimethyl-
sulfidegold(I) chloride (0.231 g, 0.783 mmol) was added as a solid to a
solution (5 mL) of 1 (0.318 g, 0.783 mmol) in toluene. The light-yellow
solution was left to stir for 2 h. Volatiles were removed under reduced
pressure and the product was washed with pentane (3ꢂ5 mL) to yield a
spectroscopically pure tan powder (0.446 g, 0.699 mmol, 89%). Crystals
suitable for study by X-ray diffraction were grown at room temperature
under nitrogen by slow vapour diffusion of pentane into a saturated solu-
tion in THF. 1H NMR (400 MHz, [D8]THF): d=7.62 (d, 3J=1.6 Hz, 1H;
NCHCHN(mesityl)), 7.26 (d, 3J=1.6 Hz, 1H; NCHCHN(mesityl)), 7.01–6.87
(m, 5H; p-CH(2,6-xylyl) +m-CH(mesityl) +m-CH(2,6-xylyl)), 2.32 (s, 3H; o-
CH3(mesityl)), 2.28 (brs, 6H; o-CH3(2,6-xylyl)), 2.05 (s, 3H; o-CH3(mesityl)), 1.60
(s, 9H; (CH3)3C), 1.39 ppm (s, 3H; m-CH3(mesityl)); 13C NMR (100 MHz,
[D8]THF): d=152.8 (NCN), 156.9 (C=N), 144.5 (i-C(2,6-xylyl)), 141.6 (i-
C(mesityl)), 135.9 (p-C(mesityl)), 130.8 (o-C(mesityl)), 130.6 (o-C(mesityl)), 121.3 (o-
C(2,6-xylyl)), 128.9 (m-C(2,6-xylyl)), 128.5 (m-CH(mesityl)), 125.1 (p-CH(2,6-xylyl)),
122.5 (NCCN(mesityl)), 120.3 (NCCN(mesityl)), 42.2 (C
(CH3)3), 21.3 (o-CH3(mesityl)), 19.4 (o-CH3(2,6-xylyl)), 17.9 (o-CH3(mesityl)),
17.2 ppm (p-CH3(mesityl)); FTIR (cast film): n˜C N =1665, n˜C 1194 cmÀ1; el-
ACHTUGNTREN(UNNG CH3)3), 29.5 (C-
AHCTUNGTRENNUNG
=
=
S
emental analysis calcd (%) for C25H31N3SAuCl: C 47.06, H 4.90, N 6.59;
found: C 46.81, H 4.66, N 6.19.
Experimental Section
AHCTUNGTERG[NNUN 1,3-Bis(2,4,6-trimethylphenyl)imidazole-2-thione]gold chloride, [(IMes-
S)AuCl] (5): Dimethylsulfidegold(I) chloride (79.6 mg, 0.270 mmol) was
added as a solid to a solution (5 mL) of 4 (91.1 mg, 0.272 mmol) in tol-
uene. The light-yellow solution was left to stir for 2 h. Volatiles were re-
moved under reduced pressure and the product was washed with pentane
General considerations: All experiments were performed under dinitro-
gen by using standard Schlenk line techniques or in an inert-atmosphere
glove box. Solvents used in the preparation of air- and/or moisture-sensi-
tive compounds were dried by using an MBraun Solvent Purification
System fitted with alumina columns and stored over molecular sieves
under a positive pressure of dinitrogen. Deuterated solvents were de-
gassed by using three freeze–pump–thaw cycles and were vacuum distil-
led from sodium (C6D6 and [D8]THF) or CaH2 (CDCl3 and CD3CN).
Phenylacetylene and all aniline substrates were degassed by using three
freeze–pump–thaw cycles before use. NMR spectra were recorded on
either a Bruker 400 (1H at 400 MHz, 13C at 100 MHz) or a Bruker 300
(1H at 300 MHz, 13C at 75.5 MHz) spectrometer. The spectra were refer-
enced internally relative to the residual protio-solvent resonances and
chemical shifts were reported with respect to d=0 ppm for tetramethylsi-
lane. Elemental compositions and exact masses were determined by
Guelph Chemical Laboratories, Inc., located in Guelph, Ontario.
(3ꢂ5 mL) to yield
a spectroscopically pure tan powder (0.446 g,
0.801 mmol, 89%). Crystals suitable for study by X-ray diffraction were
grown at room temperature under nitrogen by slow vapour diffusion of
1
pentane into a saturated solution in THF. H NMR (400 MHz, C6D6): d=
6.77 (s, 4H; m-CH), 5.62 (s, 2H; NCHCHN), 2.18 (s, 6H; p-CH3),
1.86 ppm (s, 3H; o-CH3); 13C NMR (100 MHz, C6D6): d=155.2 (NCN),
141.1 (p-C), 135.0 (i-C), 132.4 (o-C), 130.3 (m-C), 120.3 (NCCN), 21.3 (p-
CH3), 17.6 ppm (o-CH3); FTIR (cast film) n˜C S =1071 cmÀ1; elemental
=
analysis calcd (%) for C21H24N2SAuCl: C 44.33, H 4.25, N 5.08; found: C
44.19, H 4.52, N 4.92.
{1-[(2,6-Dimethylphenylimino)-2,2-dimethylpropyl]-3-(2,4,6-trimethylphe-
nyl)imidazol-2-ylidene}gold chloride, [(C^IminetBu)AuCl] (6): C^IminetBu
(1; 122 mg, 0.326 mmol) was dissolved in toluene (6 mL) and solid dime-
thylsulfidegold(I) chloride (96.1 mg, 0.326 mmol) was added in small por-
tions. The reaction mixture was stirred for 2 h at room temperature.
Excess solvent was removed under vacuum. The sample was then dis-
solved in a minimal amount of THF, filtered through a plug of Celite and
pentane was added to the filtrate to precipitate the product. The product
was isolated by filtration and washed with pentane to give 6 as a spectro-
scopically pure off-white solid (156 mg, 0.258 mmol, 79%). Crystals suita-
ble for study by X-ray diffraction were grown at room temperature under
nitrogen by layering pentane onto a saturated solution in THF. 1H NMR
(400 MHz, C6D6): d=6.79 (brs, 2H; m-CH(2,6-xylyl)), 6.73 (t, 3J=6.8 Hz,
1H; p-CH(2,6-xylyl)), 6.51 (s, 2H; m-CH(mesityl)), 6.18 (d, 3J=1.8 Hz, 1H;
NCHCHN(mesityl)), 5.68 (d, 3J=1.8 Hz, 1H; NCHCHN(mesityl)), 2.74 (brs,
3H; o-CH3(mesityl)), 1.96 (s, 3H; p-CH3(mesityl)), 1.77 (brs, 6H; o-CH3(2,6-
Elemental sulfur, 2,6-dimethylaniline, 2,4,6-trimethylaniline, 2,6-diisopro-
pylaniline, aniline, para-anisidine and para-(trifluoromethyl)aniline were
purchased from Alfa Aesar. Dimethylsulfidegold(I) chloride, phenylace-
tylene, 2-tert-butylaniline, para-methylaniline and para-nitroaniline were
purchased from Sigma–Aldrich. AgBF4 was purchased from Strem.
[19]
[(C^ImineMe)AgCl],[20] C^IminetBu
,
[(IMes)AuCl][24] and IMesS[27,28]
were prepared by using literature procedures.
1-[(2,6-Dimethylphenylimino)-2,2-dimethylpropyl]-3-(2,4,6-trimethylphe-
nyl)imidazole-2-thione, S^IminetBu (2): Sulfur (12.7 mg, 0.395 mmol) was
added as a solid to a solution (3 mL) of 1 (148 mg, 0.395 mmol) in tol-
uene. The clear, light-yellow solution was allowed to stir for 2.5 h. Vola-
tiles were removed under reduced pressure and the product was washed
with pentane (3ꢂ5 mL) to yield a spectroscopically pure beige powder
(136 mg, 0.334 mmol, 85%). Crystals suitable for study by X-ray diffrac-
xylyl)), 1.38 (s, 9H;
CACTHNUGTREN(NUG CH3)3(imine)), 1.33 ppm (brs, 3H; o-CH3(mesityl));
&
8
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Chem. Eur. J. 0000, 00, 0 – 0
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