Helvetica Chimica Acta – Vol. 96 (2013)
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M.p.: micro-melting-point apparatus; uncorrected. FT-IR Spectra: JASCO-410 IR Spectrophotometer;
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in cmꢀ1. H- and 13C-NMR spectra: Bruker Avance 300 MHz spectrometer; in CDCl3; d in ppm rel. to
Me4Si, J in Hz. Elemental analysis: Vario-EL-CHNS elemental analyzer. All microwave irradiations
were carried out in the cavity of a commercially available CEM Discover apparatus. All the products
were identified by comparison of their spectra, melting points, and anal. data with those in the literature.
Synthesis of 2-(3-Arylacryloyl)phenyl Methanesulfonates 1a – 1j. General Procedure. To a suspension
of chalcone (0.01 mol) in Et3N (10 ml), methanesulfonyl chloride (MsCl; 0.05 mol) was added dropwise,
and the mixture was warmed and kept overnight. The solid, that separated on adding ice-cold H2O, was
filtered, washed with cold H2O, dried, and crystallized from aq. EtOH.
Data of 2-(3-Phenylprop-2-enoyl)phenyl methanesulfonate (1a). M.p. 1448 (AcOEt/petroleum ether
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(PE)). Yield: 74%. IR: 1648 (CO), 1379 (asym. SO2Me), 1155 (sym SO2Me), 1541. H-NMR: 3.60 (s,
SO2Me); 6.12 (d, J ¼ 13.8, Ha); 6.54 (d, J ¼ 13.8, Hb); 7.25 – 7.74 (m, 9 arom. H). 13C-NMR: 38.1; 116.5;
117.4 (C(a)); 122.6; 123.1; 125.2; 127.7; 128.4; 136.3; 148.4 (C(b)); 156.9; 193.1 (CO). Anal. calc. for
C16H14O4S (302.35): C 63.56, H 4.67; found: C 63.58, H 4.65.
Synthesis of 2-(3-Aryloxirane-2-carbonyl)phenyl Methanesulfonates 2a – 2j. General Procedure. To a
stirred soln. of 1a – 1j (0.01 mol) in EtOH (30.0 ml) kept at 58, 30% H2O2 soln. (0.05 mol) and aq. NaOH
(5%, 0.05 mol) were added in succession, while maintaining the temp. of the mixture at 58, and stirring
was continued for 4 h. The solid that separated was filtered, washed with H2O, dried, and crystallized
from aq. EtOH.
Data of 2-[(3-Phenyloxirane-2-yl)carbonyl]phenyl Methanesulfonate (2a). Yellow needles. M.p.
123 – 1248 (EtOH). Yield: 75%. IR: 1662 (CO), 1383 (asym. OSO2), 1184 (sym OSO2), 1261 (asym.
COC), 1080 (sym. COC). 1H-NMR: 3.62 (s, SO2Me); 4.61 (d, J ¼ 2.7, Hb); 4.85 (d, J ¼ 2.7, Ha); 7.43 – 7.71
(m, 9 arom. H). 13C-NMR: 37.5 (SO2Me); 59.0; 67.5; 114.3; 122.0; 123.3; 124.7; 127.0; 128.5; 137.7; 157.8;
192.9 (CO). Anal. calc for C16H14O5S (318.34): C 60.37, H 4.43; found: C 60.38, H 4.41.
Representative Procedure for the Synthesis of 2-Aryl-3-hydroxy-4H-chromen-4-ones 3a – 3j. An
intimate mixture of 2a – 2j and montmorillonite KSF clay in a 1:3 ratio (w/w) was charged in a
microwave (MW) test tube placed in a MW cavity and irradiated with MWs at 1208 (power, 200 W) for
2 – 3 min (Table). The course of the reaction was followed by TLC. After the disappearance of the
starting material, the MW test tube was removed, cooled to r.t., and the residue was stirred with H2O and
extracted with CHCl3. The CHCl3 extract was washed with H2O, dried, and purified by passing through a
small column of SiO2. Evaporation of the solvent gave pure 2-aryl-3-hydroxy-4H-chromen-4-ones in
> 90% yield.
Data of 3-Hydroxy-2-phenyl-4H-chromen-4-one (3a). Yield: 96%. M.p. 1708 (aq. EtOH; [8]: 170 –
1718). IR: 3383 (OH), 1659 (CO), 1607, 1576, 1551 (C¼C). 1H-NMR: 7.25 – 7.73 (m, 9 arom. H); 10.68 (s,
HOꢀC(3)). 13C-NMR: 118.3; 122.0; 125.4; 127.6; 128.9; 130.5; 134.7; 135.8; 145.8; 156.2; 172.1 (CO).
FAB-MS (pos.): 238.5 (37, Mþ), 221.4 (100), 212.0 (28), 183.1 (34), 165.0 (37), 145.1 (24), 133.0 (32),
121.1 (39), 105.2 (69). Anal. calc. for C15H10O3 (238.24): C 75.62, H 4.23; found: C 74.88, H 5.01.
Data of 2-(2-Chlorophenyl)-3-hydroxy-4H-chromen-4-one (3b). Yield: 95%. M.p. 178 – 1798 (aq.
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EtOH; [8]: 1788). H-NMR: 7.36 – 8.03 (m, 8 arom. H); 10.53 (s, HOꢀC(3)). 13C-NMR: 116.1; 121.5;
123.4; 125.2; 126.7; 129.6; 130.3; 131.3; 132.6; 135.2; 136.5; 156.2; 160.2; 173.1 (CO). Anal. calc. for
C15H9ClO3 (272.68): C 66.07, H 3.33; found: C 65.98, H 3.38.
Data of 3-Hydroxy-2-(3-nitrophenyl)-4H-chromen-4-one (3c). Yield: 90%. M.p. 203 – 2058 (aq.
EtOH; [8]: 205 – 2068). 1H-NMR: 7.70 – 8.12 (m, 8 arom. H); 10.70 (s, HOꢀC(3)). 13C-NMR: 115.4;
120.0; 121.6; 123.1; 123.4; 129.5; 131.2; 134.0; 135.2; 136.5; 146.9; 147.8; 156.2; 172.6 (CO). Anal. calc. for
C15H9NO5 (283.24): C 63.61, H 3.20; found: C 63.65, H 3.22.
Data of 3-Hydroxy-2-(4-methoxyphenyl)-4H-chromen-4-one (3d). Yield: 91%. M.p. 196 – 1978 (aq.
EtOH; [8]: 197 – 1998). 1H-NMR: 3.83 (s, MeO); 6.90 – 8.06 (m, 8 arom. H); 10.60 (s, HOꢀC(3)).
13C-NMR: 57.3 (MeO); 114.2; 115.4; 122.0; 122.8; 125.2; 128.6; 135.2; 137.5; 146.6; 156.2; 159.8; 171.8
(CO). Anal. calc. for C16H12O4 (268.26): C 71.64, H 4.51; found: C 71.62, H 4.54.
Data of 2-(4-Chlorophenyl)-3-hydroxy-4H-chromen-4-one (3e). Yield: 95%. M.p. 197 – 1988
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(MeOH; [8]: 198 – 2008). H-NMR: 7.36 – 8.10 (m, 8 arom. H); 10.53 (s, HOꢀC(3)). 13C-NMR: 115.6;
121.5; 123.3; 125.9; 127.8; 128.1; 130.2; 135.3; 136.9; 145.6; 157.1; 158.9; 171.8 (CO). Anal. calc. for
C15H9ClO3 (272.68): C 66.07, H 3.33; found: C 66.11, H 3.35.