G. A. Carriedo et al.
FULL PAPER
Soluble Fraction SF: C108H84F6AuN3O6P10 (2140.55): calcd. C
60.60, H 3.96, N 1.96; found C: 57.22, H 3.41, N 1.95. 31P NMR
(CD2Cl2): δ = 39.5 (broad, m, Au-PPh3), 30.88 (broad, m,
OC6H4PPh2-Au), 9.61 (s, N3P3), –144.10 (hp, PF6) ppm. IR (KBr):
(2ϫ5 mL) and dried. The solid residue was washed with diethyl
ether (2ϫ5 mL) and dried in vacuo for reutilisation in situ. After
the 5th cycle, the material began to be slightly soluble in diethyl
ether, so n-hexane was used instead. The absence of any residual
ketones from the previous uses was always previously checked by
GC. Conversion was 100% in the first five cycles, 97% in the 6th
and 90–45% from the 7th cycle. In the microwave experiments, re-
covery was less successful (three cycles with 100%, and 90–50%
thereafter).
ν = 3053.9 (d, υC-arom.), 2924.8 (w), 1587.8 (w), 1490.5 (m), 1435.9
˜
(s, υC=Carom), 1307.3 (vw), 1269.6 (w, υPO-C), 1207.1 (s), 1187.6 (s),
1165.2 (vs, υPN), 1118.2 (m), 1096.4 (m, υP-OC), 953.8 (s), 883.8 (w),
837.6 (vs, υPF), 744.1 (m, δPNP), 693.6 (s), 559.0 (m, δPF) cm–1.
3. Catalytic Studies: All experiments were carried out in a sealed
Young tube under N2, with deoxygenated solvents (see the repre-
sentative example below). The reagents were introduced in the fol-
lowing order: the catalyst, the solvents THF or MeOH or a combi-
nation of both; the alkyne, water and H2SO4. The tube was sealed
and heated at the desired temperature until all the alkyne is con-
verted into the ketone (100% conversion), as determined by GC.
The microwave experiments were carried out with magnetic stirring
in a CME-DISCOVERER S-CLASS system setting the maximum
power at 150 W and the pressure at 250 psi.
e) Thermal and Microwave-Assisted Hydration with C3: 1-Octyne
(18 μL, 0.125 mmol), C3 (10 mg = 0.0117 mmol [Au+] = 9.5 mol-
% with respect to the alkyne), methanol (2 mL), water (20 μL,
1.11 mmol), THF (100 μL) and H2SO4 (1.0 μL, 0.017 mmol). The
mixture was heated at 150 °C for 16 h (conversion 100%). Recuper-
ation and reuse was performed as for C2. 100% conversion was
observed in three cycles dropping to 75% in the 4th cycle.
Note: Under the same thermal conditions used for 1-octyne, the
alkynes p-Cl-C6H4-CϵCH and C6H5-CϵCH were completely hy-
drated in 12 h. Using microwave radiation at 150 °C the reaction
was completed (100%) in 10 h or in 2 h using 50 mol-% of H2SO4.
Hydration of 1-Octyne: (MW 110.2 g/mol, density 0.747 g/cm3).
a) Thermal Hydration with C1: 1-Octyne (37 μL, 0.25 mmol),
[Au(PPh3)2]PF6 (C1) (4 mg, 0.0046 mmol), methanol (0.5 mL),
water (0.5 mL, 27.8 mmol), H2SO4 (2 μL, 0.037 mmol). The tube
was sealed and heated at 100 °C. After 12 h 100% conversion to 2-
octanone was observed.
Acknowledgments
We are grateful to the Spanish Dirección General de Investigación
Ciencia y Técnica (DGICYT) (project CTQ2007-6118), Juan de la
Cierva Contract (grants to S. L. and A. P. S.) and the Marie Curie
RG program (grant to A. P. S.) for financial support. We also thank
Dr. M. L. Valenzuela (Universidad Andres Bello, Chile) for her
assistance with the samples of catalyst C1.
Note: No conversion took place in the absence of methanol or
THF. Using 2 mg of C1 (ca. 1 mol-%) the conversion was 45% in
16 h. Using no C1, conversion was 10% in 16 h. Using no H2SO4,
conversion was 6% in 16 h. At room temperature, conversion was
70% in 15 d with 1% of C1. Under the same conditions used for
1-octyne, the alkynes p-PhO-C6H4-CϵCH, C6H5-CϵCH, p-Cl-
C6H4-CϵCH, and C6H5-CH2-CϵCH, were hydrated to the corre-
sponding ketones in 5, 7, 9 and 10 h, respectively.
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Guan, D. Xing, G. Cai, X. Wan, N. Yu, Z. Fang, L. Yang, Z.
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b) Microwave-Assisted Hydration with C1: 1-Octyne (37 μL,
0.25 mmol), [Au(PPh3)2]PF6 (C1) (4 mg, 0.0046 mmol), methanol
(0.5 mL), water (0.5 mL), H2SO4 (2 μL, 0.0368 mmol). The tube
was heated at 100 °C with microwaves for 1 h. The conversion to
2-octanone was 100%. Identical result was obtained with THF as
solvent.
Note: The same experiment excluding the gold catalyst (C1) gave
4% conversion in 1 h. At 150 °C, using methanol and 50 mol-% of
H2SO4 in the absence of C1, the alkynes p-PhO-C6H4-CϵCH,
C6H5-CϵCH, p-Cl-C6H4-CϵCH, and C6H5-CH2-CϵCH, were hy-
drated in 5 min, 30 min, 1 h, and 6 h, respectively.
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c) Thermal and Microwave-Assisted Hydration with C2: 1-Octyne
(74 μL, 0.5 mmol), C2 (40 mg, 0.01 mmol [Au+] = 1.92 mol-% with
respect to the alkyne), THF (2 mL), methanol (0.15 mL), water
(0.15 mL, 8.3 mmol), H2SO4 (98 μL, 1.8 mmol). The addition of
the acid caused the catalyst to go into solution. The mixture was
heated at 100 °C for 16 h (100% conversion).
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Note: In the experiments excluding the catalysts C1, conversion
was less than 18% in 16 h. Under the same thermal conditions used
for 1-octyne, the alkynes p-Cl-C6H4-CϵCH and C6H5-CϵCH were
hydrated in 1 h 30 min and 1 h 15 min, respectively. Using micro-
wave radiation for the heating, 1-octyne was completely hydrated
in 1 h 45 min. As noted above, the other alkynes can be hydrated
in much shorter times in the absence of the gold(I) catalyst.
d) Recovery of the Catalyst C2 for Further Use: The reaction mix-
ture was concentrated to 1/3 of its volume. Then, water (10 mL)
and CH2Cl2 (2.5 mL) were added and, after stirring, the aqueous
layer was removed. The organic layer was washed with water
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