General procedure for the preparation of coumaran-2-one 2 and
comparative studies
2 R. Giguere, T. Bray, S. Duncan and G. Majetich, Tetrahedron Lett.,
1
986, 27, 4945.
3
A. Bose, M. Manhas, M. Manta-Shah, V. Raju, S. Bari, S. Newaz,
All operations were repeated at least thrice to control the repro-
ducibility of the cyclisation under each particular set of condi-
tions. All yields were calculated by weighing the synthesised 2.
B. Banik, A. Chaudhary and K. Barakat, J. Org. Chem., 1991,
5
6, 6968. (“MORE” Chemistry is “Microwave-Induced Organic
Reaction Enhancement Chemistry”).
4
5
A. Bose, M. Manhas, B. Banik and E. Robb, Res. Chem. Intermed.,
1
994, 20, 1.
Classical heating. 2-Hydroxyphenylacetic acid 1 (5g, 33
mmol) was ground alone or together with toluene-p-sulfonic
acid monohydrate (0.125g, 0.66 mmol) and the solid mixture
placed in the microwave reactor. The vessel was immersed in a
preheated silicone oil bath for the appropriate time. After cool-
D. Villemin and B. Labiad, Synth. Commun., 1990, 20, 3333.
6 G. Bram, A. Loupy and M. Madjoub, Tetrahedron, 1990, 46, 5167.
7 D. Villemin and A. Ben Alloum, Synth. Commun., 1991, 21, 63.
8
9
D. Villemin, B. Martin and B. Garrigues, Synth. Commun., 1993, 23,
251.
2
D. Jinchang, G. Hengjie, W. Jinzhu and L. Caizhen, Synth.
Commun., 1994, 24, 301.
ing to room temperature, saturated sodium hydrogen carbonate
3
(
2–5 cm ) was added in order to neutralise any unreacted 1 and
1
0 D. Abenhaïm, C. Ngoc-Son, A. Loupy and N. Ba-Hiep, Synth.
Commun., 1994, 24, 1199.
11 D. Villemin and B. Martin, J. Chem. Res. (S), 1994, 146.
2 G. Bram, A. Loupy, M. Madjoub and A. Petit, Chem. Ind.
(London), 1991, 396.
3 J. F. Pilard, B. Klein, F. Texier-Boullet and J. Hamelin, Synlett,
PTSA. The precipitated lactone was then filtered, washed with
3
cold water (2 × 10 cm ) and air-dried to afford 2 as a yellow
1
1
1
solid. The lactone was quite pure as indicated by its melting
1
point and H NMR spectrum (see below).
1
992, 219.
Syntheses in a multimode oven. Chromatographic alumina
Merck 90, neutral, Art.1.01077.1000) was dehydrated under
4 J. M. Lerestif, J. Perrocheau, F. Tonnard, J. P. Bazureau and
J. Hamelin, Tetrahedron, 1995, 51, 6757.
15 U. Fernandez-Paniagua, B. Illescas, N. Martin, C. Seoane, P. De La
Cruz, A. De La Hoz and F. Langa, J. Org. Chem., 1997, 62, 3705.
6 D. Villemin, M. Hachemi and M. Lalaoui, Synth. Commun., 1996,
(
microwave heating (450 W) to constant weight and kept in a
cool dry place (desiccator over activated silica gel). 2-Hydroxy-
phenylacetic acid 1 (5 g, 33 mmol)—alone or with PTSA
monohydrate (0.125 g, 0.66 mmol)—was ground to a homo-
geneous powder and placed in the microwave vessel covered
with a watch glass in order to minimise evaporation. The
reactor was immersed in the alumina bath (100 g) and irradi-
ated for the appropriate time. The bath temperature was meas-
ured immediately after irradiation with a thermocouple (range:
Ϫ40/ϩ1000 ЊC, accuracy: ±1 ЊC). After cooling, the contents of
the vessel were worked up as above.
1
2
6, 2461.
7 G. Nagy, S. Filip, E. Surducan and V. Surducan, Synth. Commun.,
997, 27, 3736.
1
1
18 A. Souadi, J. Hamelin and H. Benhaoua, Tetrahedron Lett., 1998,
39, 4035 and cited references.
9 A. Diaz-Ortiz, E. Diez-Barra, A. De La Hoz, A. Loupy, A. Petit and
L. Sanchez, Heterocycles, 1994, 38, 795.
0 R. Saillard, M. Poux and M. Audhuy-Peaudecerf, Mater. Res. Soc.
Symp. Proc., 1996, 403, 411.
1
2
2
1 A. Loupy, D. Monteux, A. Petit, J. Aizpurua, E. Dominguez and
C. Palomo, Tetrahedron Lett., 1996, 37, 8177.
Syntheses in a monomode oven. The cyclisation was carried
out as above from 1 and PTSA, the power of the magnetron
being assigned as 300 W. The intimate mixture of 2-hydroxy-
phenylacetic acid 1 (0.76 g, 5 mmol) and PTSA monohydrate
1
(
19 mg, 0.1 mmol) gave 2 (0.57 g, 85% yield) after 6 min
35
of microwave irradiation. Mp 49 ЊC (lit., 28.5 ЊC and 49 ЊC);
νmax/cm : 1804 (C᎐O); δH (200 MHz, CDCl ) 3.74 (s, 2H),
Ϫ1
3
7
.15–7.35 (m, 4H arom).
Spectroscopic analyses of 2-hydroxyphenylacetic acid 1
Infrared spectrophotometry. The acid 1 and its admixture with
PTSA (2 mol%) exhibited the same characteristic O–H bands
Ϫ1
at 3375 and 3200 cm ; their relative intensities were approxi-
mately 2/1 and 1/1 respectively. The FT-IR and ATR spectra
differed in the position of the carbonyl band, located respect-
Ϫ1
ively at 1700 and 1715 cm .
3
5 Dictionary of Organic Compounds, Chapman and Hall, New York,
th edition, 1982, vol. 1, p. 558.
Nuclear magnetic resonance spectroscopy of 1 and 1 ؉ 2
mol% PTSA. δ (CD –SO–CD ) 34.6 (CH ), 114.3, 118.1, 121.1,
5
C
3
3
2
1
27.1, 130.2 (5 aromatic carbons), 154.7 (C-OH), 172.0
(
COOH).
References
1
R. Gedye, F. Smith, K. Westaway, H. Ali, L. Baldisera, L. Laberge
and J. Rousell, Tetrahedron Lett., 1986, 27, 279.
Paper 9/04159A
J. Chem. Soc., Perkin Trans. 2, 1999, 2111–2115
2115