1438
R. Maggi et al. / Tetrahedron 64 (2008) 1435e1439
four reaction cycles [yield (selectivity) for the model reaction:
first cycle 81% (91%), second cycle 76% (92%), third cycle
77% (92%), fourth cycle 75% (91%)].
benzaldehyde (5 mmol), the selected secondary amine
(5 mmol), the selected alkyne (5 mmol), and the AgeNaY ze-
olite (0.1 g) at 100 ꢀC for 15 h. After cooling to room temper-
ature the mixture was filtered using a Buchner funnel and the
¨
3. Conclusions
zeolite was washed with ethyl acetate (30 ml). The crude prod-
uct was then purified through a silica gel column (length:
25 cm, diameter: 4 cm) using mixtures of CH2Cl2/MeOH
(99:1 to 95:5) as eluant. Spectral data of known propargyl-
amines 4aaa, 4baa, 4caa, 4daa, 4aab, 4aac, 4eaa, and 4faa
were in accordance with literature data.10,11
In conclusion we have shown that AgeNaY zeolite can be
utilized as an efficient heterogeneous catalyst for the eco-
efficient preparation of propargylamines following a three-
component strategy. Moreover, the absence of VOC (a solvent
is required only in the work-up procedure for catalyst filtration
and washing), the easy preparation of AgeNaY zeolite (from
commercial NaY zeolite and silver nitrate) and the possibility
to recycle the catalyst for at least four times with the same
good yield and selectivity, makes this approach practical and
environmentally acceptable.
4.3.1. 1-(3-(4-Chlorophenyl)-1-phenylprop-2-
ynyl)piperidine (4aba)
Dark yellow solid; mp 55.5e57.5 ꢀC; IR (neat): 2260 cmꢃ1
;
1H NMR (300 MHz, CDCl3) d 1.39e1.50 (m, 2H), 1.52e1.70
(m, 4H), 2.50e2.62 (m, 4H), 4.79 (s, 1H), 7.25e7.48 (m,
7H), 7.61 (d, J¼7.2 Hz, 2H); 13C NMR (75 MHz, CDCl3)
d 138.17, 133.97, 132.96, 128.52, 128.43, 128.04, 127.49,
121.70, 87.11, 86.63, 62.30, 50.65, 26.04, 24.31; MS (EI, m/
z) 309 (Mþ, 25), 234 (73), 255 (100), 189 (31). Anal. Calcd
for C20H20ClN: C, 77.74; H, 6.52; N, 4.53. Found: C, 77.68;
H, 6.56; N, 4.44.
4. Experimental
4.1. Material and reagents
NaY zeolite HSZ-320 (Tosoh Corp.) is a FAU zeolite with
˚
5.6 SiO2/Al2O3 molar ratio, pore size 7.4 A and surface area
570ꢂ10 m2/g.
4.3.2. 1-(3-(4-tert-Butylphenyl)-1-phenylprop-2-
ynyl)piperidine (4aca)
The CueNaY zeolite was prepared by a conventional ion
exchange method15 in which NaY was treated with an aqueous
solution of cupric nitrate at 90 ꢀC for 5 h, washed with deion-
ized water, filtered, dried, and calcined at 500 ꢀC for 15 h in
air; loading 1.14 mmol/g.
Pale yellow solid; mp 56.5e59.0 ꢀC; IR (neat): 2210 cmꢃ1
;
1H NMR (300 MHz, CDCl3) d 1.32 (s, 9H), 1.39e1.50 (m,
2H), 1.53e1.67 (m, 4H), 2.52e2.61 (m, 4H), 4.79 (s, 1H),
7.26e7.40 (m, 3H), 7.35 (d, J¼8.4 Hz, 2H), 7.46 (d,
J¼8.4 Hz, 2H), 7.63 (d, J¼7.3 Hz, 2H); 13C NMR (75 MHz,
CDCl3) d 151.23, 138.60, 131.45, 128.50, 127.95, 127.33,
125.20, 120.25, 87.81, 85.21, 62.31, 50.56, 34.68, 31.13,
26.09, 24.37; MS (EI, m/z) 331 (Mþ, 42), 254 (82), 247
(100), 217 (32). Anal. Calcd for C24H29N: C, 87.09; H,
8.83; N, 4.23. Found: C, 86.99; H, 8.86; N, 4.32.
The AgeNaY zeolite was prepared by a conventional ion
exchange method16 in which NaY was treated with an aqueous
solution of silver nitrate at room temperature for 5 h in a dark,
washed with deionized water, filtered, dried, and calcined at
500 ꢀC for 15 h in air; loading 2.43 mmol/g.
The AueNaY zeolite was prepared by a conventional ion
exchange method17 in which NaY was treated with an aqueous
solution of chloroauric acid (maintaining the pH value
between 5 and 6 through aqueous sodium hydroxide addition)
at 80 ꢀC for 2 h, washed with deionized water, filtered, dried,
and calcined at 500 ꢀC for 15 h in air; loading 0.28 mmol/g.
Benzaldehyde was distilled under reduced pressure and
stored in a bottle under nitrogen and in the dark before use.
All other organic reagents were commercial products (Aldrich,
Fluka) and were used as such.
4.3.3. 1-(1-Phenylnon-2-ynyl)piperidine (4ada)14
Yellow oil; IR (neat): 2254 cmꢃ1 1H NMR (300 MHz,
;
CDCl3) d 0.92 (t, J¼6.8 Hz, 3H), 1.24e1.68 (m, 14H),
2.28e2.53 (m, 6H), 4.55 (s, 1H), 7.23e7.41 (m, 3H), 7.57
(d, J¼7.1 Hz, 2H); 13C NMR (75 MHz, CDCl3) d 139.04,
128.47, 127.81, 127.13, 87.88, 76.137, 61.91, 50.43, 31.78,
29.21, 29.03, 29.00, 28.86, 26.06, 24.41, 22.62, 18.75,
14.06; MS (EI, m/z) 283 (Mþ, 8), 206 (100), 128 (16). Anal.
Calcd for C20H29N: C, 84.88; H, 10.33; N, 4.95. Found: C,
84.97; H, 10.36; N, 4.90.
4.2. ICP measurement
ICP measurements were carried out on an ICP-AES Jobin
Yvon mod. 2501 Ultima 2 spectrophotometer by preparing
samples dissolving 50 mg of calcined exchanged Y zeolite
in concentrated nitric acid.
4.3.4. 1-(1-Phenylundec-2-ynyl)piperidine (4aea)14
Yellow oil; IR (neat): 2253 cmꢃ1 1H NMR (300 MHz,
;
CDCl3) d 0.89 (t, J¼6.7 Hz, 3H), 1.22e1.66 (m, 18H),
2.28e2.53 (m, 6H), 4.55 (s, 1H), 7.22e7.41 (m, 3H), 7.56
(d, J¼7.4 Hz, 2H); 13C NMR (75 MHz, CDCl3) d 139.08,
128.44, 127.78, 127.09, 87.83, 76.15, 61.90, 50.43, 31.25,
28.95, 28.51, 26.07, 24.39, 22.53, 18.73, 13.98; MS (EI,
m/z) 311 (Mþ, 5), 234 (71), 130 (100), 115 (40). Anal. Calcd
for C22H33N: C, 84.97; H, 10.70; N, 4.50. Found: C, 84.88; H,
10.66; N, 4.41.
4.3. General procedures for the three-component
synthesis of propargylamines (4)
The three-component reaction was performed by stirring
under nitrogen atmosphere a mixture of the selected