A highly practical route to 2-methylchromones from 2-acetoxybenzoic acids

Article abstract of DOI:10.1081/SCC-100104333

2-Methylchromones were accessed via a keto ester condensation on 2-acetoxybenzoyl chloride, followed by cyclization and decarboxylation. No column chromatography was required in the process.

Full text of DOI:10.1081/SCC-100104333

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A HIGHLY PRACTICAL ROUTE TO 2-
METHYLCHROMONES FROM 2-ACETOXYBENZOIC ACIDS
Jae-Chul Jung a , Jong-Pil Min a & Oee-Sook Park b
a Department of Chemistry , College of Natural Sciences, Chungbuk National University ,
Cheongju 361-763, Chungbuk, Korea
b Department of Chemistry , College of Natural Sciences, Chungbuk National University ,
Cheongju 361-763, Chungbuk, Korea
Published online: 16 Aug 2006.
To cite this article: Jae-Chul Jung , Jong-Pil Min & Oee-Sook Park (2001) A HIGHLY PRACTICAL ROUTE TO 2-
METHYLCHROMONES FROM 2-ACETOXYBENZOIC ACIDS, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 31:12, 1837-1845, DOI: 10.1081/SCC-100104333
To link to this article: http://dx.doi.org/10.1081/SCC-100104333
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SYNTHETIC COMMUNICATIONS, 31(12), 1837–1845 (2001)
A HIGHLY PRACTICAL ROUTE TO
2-METHYLCHROMONES FROM
2-ACETOXYBENZOIC ACIDS
Jae-Chul Jung,Jong-Pil Min,and Oee-Sook Park
*
Department of Chemistry, College of Natural Sciences,
Chungbuk National University, Cheongju 361-763,
Chungbuk, Korea
ABSTRACT
2-Methylchromones were accessed via a keto ester condensa-
tion on 2-acetoxybenzoyl chloride, followed by cyclization
and decarboxylation. No column chromatography was
required in the process.
As part of our synthetic program towards the synthesis of non-peptide
human immunodeficiency virus (HIV) protease inhibitors, practical
synthesis of 2-methylchromones (1) was needed for large scale production.
There are a number of reported methodologies1–7 for the synthesis of
2-methylchromones due to their pharmaceutical importance.8a–j These
synthetic routes were based on (i) the base catalyzed 1,3 diketone Claisen
condensation, (ii) the Friedel-Crafts acylation of phenol in presence of
POCl3, (iii) the intramolecular Witting reaction, and (iv) the internal cycli-
zation of 2-hydroxyaryl phenylethynyl ketones.
* Corresponding author.
1837
Copyright & 2001 by Marcel Dekker, Inc.
www.dekker.com

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JUNG,MIN,AND PARK
Most of these methods have drawbacks such as tedious work-up, poor
to moderate yield and use of expensive reagents. We report here a synthesis
of 2-methylchromones in only three steps from readily available starting
materials which required no purification of intermediates and the final pro-
duct was easily purified by recrystallization.
(a) Ac2O, pyridine; (b) SOCl2, urea/toluene; (c) CH2(CO2Et)2, Mg, EtOH;
(d) CH3COCH2CO2Et, 40% NaOH; (e) p-TsOH/H2O; (f ) 6N HCl; (g) 3 N
HCl/EtOH.
Scheme.
The synthesis started from a well known ethyl acetoacetate synthesis
(or malonic ester synthesis) between ethyl acetoacetate (or diethyl malonate)
and 2-acetoxybenzoyl chloride which was prepared from 2-hydroxybenzoic
acid (Scheme). The resulting ethyl 2-methyl-4-oxo-4H-benzopyran-
3-carboxylates (5) were hydrolyzed and decarboxylated to give 2-methyl-
chromones (1). All the compounds were fully characterized. Physical
properties for 2-methylchromones (1a–g) are presented in Table 1.

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1839
Table 1. Physical Data of the 2-Methylchromones
Mp (ꢀC)
(found/reported)
Compd.
R1
R2
Methoda
Yield (%)b
1a
1b
1c
1d
1e
1f
H
H
OMe
Cl
BR
I
I
Me
OMe
H
H
H
A
A
A
B
B
C
C
113–114/(114)9a–c
124/(123–124)9d
116–118
114–116/(115)9e
170–171/(171)9f
189–192 (subl)c
228 (dec)d
60
51
53
50
55
56
49
H
I
1g
(a) Recrystallized method A: ethyl acetate/ether; method B: ethanol; method C:
methanol/chloroform. (b) Isolated overall yield. (c) Sublimation. (d) Decomposition.
In summary, we have devised a short, convenient route to quickly
access 2-methylchromones with a variety of groups in the benzene ring.
The synthesis can be accomplished on a large scale without purification of
any intermediates.
EXPERIMENTAL
Reactions requiring anhydrous conditions were performed with the
usual precautions for rigorous exclusion of air and moisture. 1H NMR
and 13C NMR spectra were recorded on a Brucker DPX 300 at 300 MHz
and 76 MHz, respectively. The chemical shifts were reported in parts per
million (ppm) downfield from tetramethylsilane, and J-values were in Hz.
IR spectra were obtained on a Jasco FT/IR-300E spectrometer. All mps
were uncorrected. When necessary, chemicals were purified according to
the reported procedure.10
General Procedure for the Preparation of Diethyl 2-{hydroxy
[2-(acetoxy)phenyl]methylene} malonate Derivatives (4a–g)
A solution of (10.0 mmol) of 2-hydroxybenzoic acids in (40.0 mmol) of
anhydrous pyridine was treated with (40.0 mmol) of acetic anhydride. The
resulting solution was stirred at room temperature for 10 h. The solution
was poured into ice-H2O and extracted with CH2Cl2. The organic extracts
were washed with cold 5% aq. HCl solution, sat’d NaHCO3 solution and

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JUNG,MIN,AND PARK
brine two times, respectively. The organic layer was dried over anhydrous
MgSO4 and concentrated to give a pale yellow solid, to which thionyl
chloride (11.0 mmol) and urea (15 mg) in 2.2 mL of anhydrous toluene
were added at 10–15ꢀC. The reaction mixture was heated in an oil bath at
100–110ꢀC for 3 h, then cooled to room temperature. The mixture of diethyl
malonate (10.0 mmol), magnesium (10.1 mmol), ethanol (30.3 mmol), CCl4
(0.1 mL) and anhydrous toluene (20 mL) was refluxed for 1 h and then
cooled to 0–5ꢀC. The former solution was cannulated into the latter. The
resulting reaction mixture was stirred at room temperature for 30 min, and
then cooled to 0–5ꢀC. 10 mL of 1N HCl was added. The organic layer was
washed with brine, dried and concentrated under reduced pressure.
Diethyl
2-{hydroxy[3-methyl-2-(acetoxy)phenyl]methylene}malonate
(4a). Rf ¼ 0.45 (hexane/ethyl acetate ¼ 3/1); 91% yield; IR (ꢀmax, KBr)
1
3420, 2978, 1732, 1680, 1216 cmꢁ1; H NMR (CDCl3) d 13.58 (br s, 1 H),
7.62 ꢂ 7.18 (m, 3 H), 4.32 (q, J ¼ 7.13 Hz, 2 H), 4.24 (q, J ¼ 7.12 Hz, 2H),
2.28 (s, 3 H), 2.19 (s, 3H), 1.35 (t, J ¼ 7.13 Hz, 3 H), 1.24 (t, J ¼ 7.12 Hz, 3 H);
13C NMR (CDCl3) d 174.91, 171.12, 168.66, 164.82, 148.24, 135.95, 133.06,
129.31, 126.89, 125.80, 101.77, 62.35, 61.47, 20.64, 16.23, 14.07, 13.65
Diethyl 2-{hydroxy[3-methoxy-2-(acetoxy)phenyl]methylene}malonate
(4b). Rf ¼ 0.41 (hexane/ethyl acetate ¼ 3/1); 87% yield; IR (ꢀmax, KBr)
1
3389, 2990, 1728, 1652, 1108 cmꢁ1; H NMR (CDCl3) d 13.56 (br s, 1 H),
7.41 ꢂ 7.06 (m, 3 H), 4.25 (q, J ¼ 7.14 Hz, 2 H), 4.11 (q, J ¼ 7.14 Hz, 2 H),
3.83 (s, 3 H), 2.04 (s, 3 H), 1.36 (t, J ¼ 7.14 Hz, 3 H), 1.25 (t, J ¼ 7.14 Hz,
3 H); 13C NMR (CDCl3) d 174.24, 171.08, 168.22, 164.66, 151.59, 137.32,
126.43, 121.38, 116.92, 114.35, 102.08, 62.36, 60.38, 56.18, 20.70, 14.20, 13.48
Diethyl 2-{hydroxy[5-methoxy-2-(acetoxy)phenyl]methylene}malonate
(4c). Rf ¼ 0.46 (hexane/ethyl acetate ¼ 3/1); 90% yield; IR (ꢀmax, KBr)
1
3426, 2966, 1730, 1648, 1210 cmꢁ1; H NMR (CDCl3) d 13.55 (br s, 1 H),
7.66 ꢂ 7.21 (m, 3 H), 4.36 (q, J ¼ 7.14 Hz, 2 H), 4.27 (q, J ¼ 7.12 Hz, 2 H),
3.79 (s, 3 H), 2.28 (s, 3H), 1.36 (t, J ¼ 7.14 Hz, 3 H), 1.27 (t, J ¼ 7.12 Hz, 3 H);
13C NMR (CDCl3) d 176.28, 172.36, 169.59, 165.72, 151.69, 139.51, 126.50,
121.36, 117.81, 115.64, 101.08, 61.24, 60.12, 57.61, 19.88, 14.10, 13.16
Diethyl 2-{hydroxy[5-chloro-2-(acetoxy)phenyl]methylene}malonate (4d).
Rf ¼ 0.33 (hexane/ethyl acetate ¼ 5/1); 86% yield; IR (ꢀmax, KBr) 3316,
1
2986, 1722, 1688, 1180 cmꢁ1; H NMR (CDCl3) d 13.72 (br s, 1 H), 8.08
(dd, J ¼ 2.61 Hz, J ¼ 2.64 Hz, 1 H), 7.58 (dd, J ¼ 2.79 Hz, J ¼ 2.62 Hz, 1 H),
7.09 (dd, J ¼ 8.93 Hz, J ¼ 8.62 Hz, 1 H), 4.22 (q, J ¼ 7.14 Hz, 2 H), 4.13 (q,
J ¼ 7.13 Hz, 2 H), 2.36 (s, 3 H), 1.38 (t, J ¼ 7.14 Hz, 3 H), 1.29 (t, J ¼ 7.13 Hz,
3 H); 13C NMR (CDCl3) d 174.62, 168.46, 165.80, 162.77, 150.22, 136.41,
135.88, 129.81, 122.56, 118.11, 99.85, 61.23, 60.89, 20.04, 14.22, 13.89
Diethyl 2-{hydroxy[5-bromo-2-(acetoxy)phenyl]methylene}malonate (4e).
Rf ¼ 0.36 (hexane/ethyl acetate ¼ 5/1); 90% yield; IR (ꢀmax, KBr) 3378,

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2-METHYLCHROMONES
1841
2980, 1728, 1640, 1098 cmꢁ1; 1H NMR (CDCl3) d 13.52 (br s, 1 H), 8.28 (dd,
J ¼ 2.86 Hz, J ¼ 2.86 Hz, 1 H), 7.76 (dd, J ¼ 2.65 Hz, J ¼ 2.65 Hz, 1 H), 7.08
(dd, J ¼ 7.88 Hz, J ¼ 7.90 Hz, 1 H), 4.28 (q, J ¼ 7.12 Hz, 2 H), 4.16 (q,
J ¼ 7.12 Hz, 2 H), 2.25 (s, 3 H), 1.29 (t, J ¼ 7.12 Hz, 3 H) 1.24 (t, J ¼ 7.12 Hz,
3 H); 13C NMR (CDCl3) d 171.48, 168.19, 166.54, 162.38, 149.61, 136.73,
135.04, 125.68, 123.47, 119.57, 101.04, 62.71, 61.63, 20.87, 14.72, 13.81
Diethyl 2-{hydroxy[5-iodo-2-(acetoxy)phenyl]methylene}malonate (4f).
Rf ¼ 0.30 (hexane/ethyl acetate ¼ 5/1); 88% yield; IR (ꢀmax, KBr) 3411,
1
2977, 1734, 1644, 1235 cmꢁ1; H NMR (CDCl3) d 13.68 (br s, 1 H), 8.16
(dd, J ¼ 2.83 Hz, J ¼ 2.83 Hz, 1 H), 7.59 (dd, J ¼ 2.70 Hz, J ¼ 2.70 Hz, 1 H),
6.85 (dd, J ¼ 8.10 Hz, J ¼ 8.10 Hz, 1 H), 4.33 (q, J ¼ 7.13 Hz, 2 H), 4.21 (q,
J ¼ 7.15 Hz, 2 H), 2.30 (s, 3 H), 1.35 (t, J ¼ 7.13 Hz, 3 H), 1.24 (t, J ¼ 7.15 Hz,
3 H); 13C NMR (CDCl3) d 172.10, 168.49, 166.82, 161.28, 150.06, 135.86,
135.02, 126.24, 123.50, 120.11, 102.34, 61.76, 60.88, 20.04, 14.18, 13.72
Diethyl 2-{hydroxy[3,5-diiodo-2-(acetoxy)phenyl]methylene}malonate
(4g). Rf ¼ 0.38 (hexane/ethyl acetate ¼ 5/1); 84% yield; IR (ꢀmax, KBr)
1
3482, 2981, 1733, 1670, 1223 cmꢁ1; H NMR (CDCl3) d 13.71 (br s, 1 H),
8.22 (s, 1 H), 7.77 (s, 1 H), 4.37 (q, J ¼ 7.14 Hz, 2 H), 4.27 (q, J ¼ 7.14 Hz,
2 H), 2.31 (s, 3 H), 1.36 (t, J ¼ 7.14 Hz, 3 H), 1.27 (t, J ¼ 7.14 Hz, 3 H);
13C NMR (CDCl3) d 171.87, 170.98, 167.55, 163.33, 148.72, 138.09,
130.97, 125.91, 102.18, 93.40, 90.33, 62.70, 61.20, 20.96, 14.04, 13.71
General Procedure for the Preparation of Ethyl 2-methyl-4-oxo-4H-
benzopyran-3-carboxylate Derivatives (5a–g)
Method A
A solution of (20.0 mmol) of 2-hydroxybenzoic acid in (80.0 mmol)
of anhydrous pyridine was treated with (80.0 mmol) of acetic anhydride.
The resulting solution was stirred at room temperature for 10 h. The solu-
tion was poured into ice-H2O and extracted with CH2Cl2. The organic
extracts were washed with cold 5% aq. HCl solution, sat’d NaHCO3
solution and brine two times, respectively. The organic layer was dried
over anhydrous MgSO4 and concentrated to give a pale yellow solid
which was added to (22.0 mmol) of thionyl chloride and urea (30 mg) in
4.4 mL of anhydrous toluene at 10–15ꢀC. The reaction mixture was
heated in an oil bath at 100–110ꢀC for 3h, then cooled to room temperature.
The mixture of ethyl acetoacetate (20.0 mmol), magnesium (20.2 mmol),
ethanol (60.6 mmol), CCl4 (0.2 mL) and anhydrous ether (20 mL) was
refluxed for 2 h and then cooled to 0–5ꢀC. The former solution was cannu-
lated into the latter. The resulting reaction mixture was stirred at room

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JUNG,MIN,AND PARK
temperature for 30 min, and then cooled to 0–5ꢀC. 10 mL of 1N HCl was
added. The organic layer was washed with brine, dried and concentrated
under reduced pressure.
Method B
A mixture of diethyl 2-{hydroxy[2-(acetoxy)phenyl]methylene} malo-
nate (40.0 mmol), p-TsOH (0.8 g) and H2O (160 mL) was refluxed for 3 h.
The product was cooled to room temperature and filtered by suction. The
product was washed with water, dried in the air to afford pale yellowish
crystal.
Ethyl 2,8-dimethyl-4-oxo-4H-benzopyran-3-carboxylate (5a). Rf ¼ 0.32
(hexane/ethyl acetate ¼ 5/1); 79% yield; mp 159ꢀC; IR (ꢀmax, KBr) 2985,
1732, 1635, 1207 cmꢁ1
;
1H NMR (CDCl3) d 8.02 (d, J ¼ 7.86 Hz, 1 H),
7.48 (d, J ¼ 7.43 Hz, 1 H), 7.27 (d, J ¼ 7.76 Hz, 1 H), 4.42 (q, J ¼ 7.14 Hz,
2 H), 2.53 (s, 3 H), 2.46 (s, 3 H), 1.40 (t, J ¼ 7.14 Hz, 3 H); 13C NMR (CDCl3)
d 172.70, 164.29, 163.23, 152.06, 132.92, 125.11, 123.01, 121.62, 121.25,
115.93, 59.68, 17.49, 13.41, 12.24
Ethyl 8-methoxy-2-methyl-4-oxo-4H-benzopyran-3-carboxylate (5b).
Rf ¼ 0.33 (hexane/ethyl acetate ¼ 5/1); 71% yield; mp 110 ꢂ 112ꢀC; IR
(ꢀmax, KBr) 2961, 1726, 1648, 1196 cmꢁ1 1H NMR (CDCl3) d 7.55 (d,
;
J ¼ 3.05 Hz, 1 H), 7.35 (d, J ¼ 9.06 Hz, 1 H), 7.24 (d, J ¼ 8.79 Hz, 1 H),
4.42 (q, J ¼ 7.13 Hz, 2 H), 3.88 (s, 3 H), 2.51 (s, 3 H), 1.40 (t, J ¼ 7.13 Hz,
3 H); 13C NMR (CDCl3) d 174.25, 166.39, 165.33, 157.14, 150.39, 124.02,
123.84, 119.16, 117.43, 105.32, 61.70, 55.92, 19.46, 14.23
Ethyl 6-methoxy-2-methyl-4-oxo-4H-benzopyran-3-carboxylate (5c).
Rf ¼ 0.31 (hexane/ethyl acetate ¼ 5/1); 76% yield; mp 96 ꢂ 97ꢀC; IR (ꢀmax
,
KBr) 2977, 1728, 1690, 1212 cmꢁ1; 1H NMR (CDCl3) d 7.62 (s, 1 H), 7.35 (d,
J ¼ 8.78 Hz, 1 H), 7.23 (d, J ¼ 7.92 Hz, 1 H), 4.40 (q, J ¼ 7.12 Hz, 2 H), 3.92
(s, 3 H), 2.54 (s, 3 H), 1.37 (t, J ¼ 7.12 Hz, 3 H); 13C NMR (CDCl3) d 178.25,
169.76, 164.56, 159.16, 154.89, 123.72, 120.94, 118.19, 118.83, 108.59, 60.98,
54.72, 19.86, 14.12
Ethyl 6-chloro-2-methyl-4-oxo-4H-benzopyran-3-carboxylate (5d).
Rf ¼ 0.36 (hexane/ethyl acetate ¼ 5/1); 72% yield; mp 133 ꢂ 134ꢀC; IR
(ꢀmax, KBr) 2981, 1730, 1688, 1189 cmꢁ1 1H NMR (CDCl3) d 7.89 (s,
;
1 H), 7.47 (d, J ¼ 8.82 Hz, 1 H), 7.28 (d, J ¼ 8.01 Hz, 1 H), 4.53 (q,
J ¼ 7.13 Hz, 2 H), 2.63 (s, 3 H), 1.47 (t, J ¼ 7.13 Hz, 3 H); 13C NMR
(CDCl3) d 176.58, 173.45, 166.68, 155.31, 135.93, 128.52, 122.40, 123.93,
121.89, 116.48, 67.41, 19.69, 14.33
Ethyl 6-bromo-2-methyl-4-oxo-4H-benzopyran-3-carboxylate (5e).
Rf ¼ 0.38 (hexane/ethyl acetate ¼ 5/1); 70% yield; mp 170 ꢂ 172ꢀC; IR

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2-METHYLCHROMONES
1843
(ꢀmax, KBr) 2986, 1731, 1680, 1198 cmꢁ1; 1H NMR (CDCl3) d 7.74 (s, 1 H),
7.48 (d, J ¼ 8.24 Hz, 1 H), 7.24 (d, J ¼ 8.24 Hz, 1 H), 4.40 (q, J ¼ 7.14 Hz,
2 H), 2.51 (s, 3 H), 1.38 (t, J ¼ 7.14 Hz, 3 H); 13C NMR (CDCl3) d 178.65,
175.83, 166.47, 156.93, 134.91, 127.59, 122.18, 119.78, 116.41, 104.45, 66.47,
20.69, 13.97
Ethyl 6-iodo-2-methyl-4-oxo-4H-benzopyran-3-carboxylate (5f). Rf ¼
(hexane/ethyl acetate ¼ 5/1); 76% yield; mp 181ꢀC; IR (ꢀmax, KBr) 2990, 1725,
1661, 1216 cmꢁ1; 1H NMR (CDCl3) d 7.68 (s, 1 H), 7.33 (d, J ¼ 6.97 Hz, 1 H),
7.18 (d, J ¼ 6.97 Hz, 1 H), 4.43 (q, J ¼ 7.13 Hz, 2 H), 2.42 (s, 3 H), 1.33 (t,
J ¼ 7.13 Hz, 3 H); 13C NMR (CDCl3) d 176.85, 172.42, 166.68, 153.43,
144.60, 137.13, 124.31, 118.69, 116.48, 88.43, 64.17, 19.69, 14.09
Ethyl 6,8-diiodo-2-methyl-4-oxo-4H-benzopyran-3-carboxylate (5g).
Rf ¼ 0.46 (hexane/ethyl acetate ¼ 1/1); 72% yield; mp 227ꢀC; IR (ꢀmax
,
KBr) 2977, 1726, 1666, 1220 cmꢁ1; H NMR (CDCl3) d 8.46 (s, 1 H), 8.38
(s, 1 H), 4.41 (q, J ¼ 7.14 Hz, 2 H), 2.58 (s, 3 H), 1.39 (t, J ¼ 7.14 Hz, 3 H);
13C NMR (CDCl3) d 180.69, 171.85, 163.57, 153.63, 151.50, 135.73, 125.34,
117.46, 89.32, 85.39, 61.35, 17.97, 14.22
1
General Procedure for the Preparation of 2-Methylchromone
Derivatives (1a–g)
A mixture of ethyl 2-methyl-4-oxo-4H-benzopyran-3-carboxylate
(40.0 mmol), 3N HCl (50 mL) and ethanol (50 mL) was refluxed for 3 h.
The reaction mixture was cooled to 10ꢀC and filtered by suction. The prod-
uct was washed with water, dried in the air to afford pale yellowish crystal.
2,8-Dimethylchromone (1a). Rf ¼ 0.28 (hexane/ethyl acetate ¼ 2/1);
82% yield; IR (ꢀmax, KBr) 2942, 1734, 1621, 1204 cmꢁ1 1H NMR
;
(CDCl3) d 8.02 (d, J ¼ 7.61 Hz, 1 H), 7.49 (d, J ¼ 7.61 Hz, 1 H), 7.26
(t, J ¼ 7.61 Hz, 1 H), 6.17 (s, 1 H), 2.47 (s, 3 H) 2.41 (s, 3 H); 13C NMR
(CDCl3) d 178.66, 165.81, 155.01, 134.39, 127.14, 125.92, 124.45, 123.26,
110.43, 20.59, 15.59
8-Methoxy-2-methylchromone (1b). Rf ¼ 0.26 (hexane/ethyl acetate ¼
1
1/1); 83% yield; IR (ꢀmax, KBr) 2955, 1730, 1668, 1191 cmꢁ1; H NMR
(DMSO) d 7.69 (d, J ¼ 9.12 Hz, 1 H), 7.56 (d, J ¼ 9.12 Hz, 1 H), 7.36 (t,
J ¼ 9.12 Hz, 1 H), 6.21 (s, 1 H), 3.94 (s, 1 H), 3.02 (s, 3 H); 13C NMR
(DMSO) d 177.50, 165.09, 158.04, 150.17, 125.91, 122.52, 119.51, 109.75,
105.01, 56.11, 22.53
6-Methoxy-2-methylchromone (1c). Rf ¼ 0.28 (hexane/ethyl acetate ¼
1
1/1); 78% yield; IR (ꢀmax, KBr) 2949, 1733, 1670, 1211 cmꢁ1; H NMR
(DMSO) d 7.58 (s, 1 H), 7.42 (d, J ¼ 8.14 Hz, 1 H), 7.39 (d, J ¼ 8.14 Hz,
1 H), 6.09 (s, 1 H), 3.87 (s, 3 H), 2.94 (s, 3 H); 13C NMR (DMSO) d

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JUNG,MIN,AND PARK
178.54, 167.08, 154.66, 150.17, 127.84, 125.42, 122.51, 109.75, 105.96, 56.22,
21.54
6-Chloro-2-methylchromone (1d). Rf ¼ 0.46 (hexane/ethyl acetate ¼
1
1/1); 80% yield; IR (ꢀmax, KBr) 2952, 1731, 1588, 1163 cmꢁ1; H NMR
(CDCl3) d 7.89 (s, 1 H), 7.47 (d, J ¼ 8.90 Hz, 1 H), 7.39 (d, J ¼ 8.90 Hz, 1 H),
5.30 (s, 1 H), 2.07 (s, 3 H); 13C NMR (CDCl3) d 179.52, 168.59, 151.86,
134.21, 130.17, 127.11, 123.22, 120.68, 110.18, 20.24
6-Bromo-2-methylchromone (1e). Rf ¼ 0.33 (hexane/ethyl acetate ¼
1
1/1); 88% yield; IR (ꢀmax, KBr) 2952, 1731, 1588, 1163 cmꢁ1; H NMR
(CDCl3) d 8.14 (s, 1 H), 7.75 (d, J ¼ 8.84 Hz, 1 H), 7.21 (d, J ¼ 8.84 Hz,
1 H), 5.33 (s, 1 H), 2.09 (s, 3 H); 13C NMR (CDCl3) d 175.75, 163.21,
153.21, 138.33, 128.58, 122.72, 117.09, 113.42, 93.63, 18.37
6-Iodo-2-methylchromone (1f ). Rf ¼ 0.46 (hexane/ethyl acetate ¼ 1/1);
83% yield; IR (ꢀmax, KBr) 2981, 1733, 1610, 1226 cmꢁ1; 1H NMR (Acetone)
d 8.19 (s, 1 H), 7.70 (d, J ¼ 7.84 Hz, 1 H), 7.45 (d, J ¼ 7.84 Hz, 1 H), 5.77 (s,
1 H), 2.14 (s, 3 H); 13C NMR (DMSO) d 179.62, 166.74, 155.11, 152.46,
130.23, 126.45, 110.84, 98.27, 90.43, 21.26
6,8-Diiodo-2-methylchromone (1g). Rf ¼ 0.24 (hexane/ethyl acetate ¼
1
1/1); 81% yield; IR (ꢀmax, KBr) 2962, 1726, 1584, 1120 cmꢁ1; H NMR
(DMSO) d 8.25 (s, 1 H), 7.92 (s, 1 H), 5.52 (s, 1 H), 2.61 (s, 3 H); 13C NMR
(DMSO) d 182.02, 168.87, 152.44, 151.56, 132.48, 125.34, 107.99, 91.51,
88.93, 20.35
ACKNOWLEDGMENT
This work has been supported by the Basic Science Research Institute
Program (BSRI-99-3433), Ministry of Education, Republic of Korea.
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Received in the USA September 20, 2000

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