A new synthesis of flavones and pyranoflavone by intramolecular photochemical Wittig reaction in water

Article abstract of DOI:10.1016/j.tetlet.2011.10.134

A new synthetic approach toward the synthesis of flavones and pyranoflavone has been developed by light induced intramolecular photochemical Wittig reaction in water onto aryloxycarbonyl groups and suitably substituted phosphonium bromides sans any phase transfer catalyst or promoter.

Full text of DOI:10.1016/j.tetlet.2011.10.134

Supporting Information
A new synthesis of flavones and pyranoflavone by intramolecular
photochemical Wittig reaction in water
Jhantu Das and Somnath Ghosh*
Department of Chemistry, Jadavpur University, Kolkata 700032, INDIA
e-mail: ghoshsn@yahoo.com
Contents:
General
S-2
S-2
Experimental Details and Characterization Data
References
S-14
S-15
1
13
H NMR, C NMR, Mass Spectra & X-ray structure
1

General:
The melting points, recorded in sulfuric acid bath, or boiling points are uncorrected.
Photochemical reactions were done using a 150 W tungsten lamp. Solvents were routinely
purified; dried and chromatographic purifications were carried out with silica gel (60-120
mesh).
Experimental Details and Characterization Data
1
-(2-Benzoyloxy-5-methylphenyl)-ethanone (2a):
O
O
Ortho-hydroxyacetophenone (3 g, 20 mmol) was taken in pyridine (20
H C
3
CH3
mL) and to it benzoyl chloride (2.81 g, 20 mmol) was added drop
o
wisely at 0 C with stirring and kept overnight. The reaction mixture
2a
O
was warmed on a water bath for 10 min and decomposed with ice cold
hydrochloric acid (1:1), a precipitate was obtained, filtered and
washed with brine (3 x 20 mL), and dried under vacuo. Crystallized from a mixture of
o
acetone and petroleum ether (60-80 C), a colorless shining granular crystals was appear
o
1
Yield: 3.90 g (77%). mp. 60-61 C; H NMR (300MHz, CDCl
.2 Hz, 2H), 7.65 (m, 2H), 7.52 (m, 2H), 7.38 (dd, J = 8.2 Hz, 0.6 Hz, 1H), 7.11 (d, J = 8.2
Hz, 1H), 2.53 (s, 3H), 2.42 (s, 3H) ppm.
3
, 22°C): δ 8.21 (dd, J = 8.4 Hz,
1
O
O
1-(2-Benzoyloxy-5-methylphenyl)-2-bromo ethanone (3a):
-(2-Benzoyloxy-5-methylphenyl)-ethanone (2.54 g, 10 mmol) was
H C
3
Br
1
taken in glacial acetic acid (20 mL) and to it bromine (1.60 g, 10
o
3a
mmol) was added drop wisely at 0 C with stirring and kept overnight
O
o
at 27 C. The reaction mixture was then added 100 g of crushed ice, a
solid product comes out, filtered and washed with brine (3 x 20 mL) and dried under vacuo,
and the residue on chromatography over silica gel afforded 3a in ethyl acetate and petroleum
o
ether (60-80 C) (15% v/v) mixture as eluent, crystallized further from a mixture of
o
dichloromethane and petroleum ether (60-80 C) as colorless shining granular crystals. Yield:
o
1
2
.30 g (69%). mp. 85-86 C; H NMR (300MHz, CDCl
3
, 22°C): δ 8.20 (m, 2H), 7.66 (m, 2H),
2

7.53 (t, J = 7.6 Hz, 2H), 7.42 (dd, J = 8.2 Hz, 1.8 Hz, 1H), 7.17 (d, J = 8.3 Hz, 1H), 4.39 (s,
2H), 2.43 (s, 3H) ppm.
1
3
C NMR (75 MHZ, CDCl , 22°C): δ 190.9, 165.0, 147.3, 136.2, 134.7, 133.9, 130.8, 130.3,
3
129.1, 128.8, 128.1, 123.8, 34.2, 20.8 ppm.
O
2
-Benzoyloxy-5-methyl-benzoyl
methyl
triphenyl
H C
3
PPh Br
3
phosphonium bromide (4a):
O
1-(2-Benzoyloxy-5-methylphenyl)-2-bromo ethanone (0.66 g, 2
mmol) was heated in dry condition with triphenyl phosphine (0.52
g, 2 mmol) for 20 min or reflux in toluene for 4h. The mass was
4a
O
crystallized from dichloromethane and ethyl acetate and 4a was obtained as colorless
o
1
granular crystals. Yield: 0.73 g (62%), mp 196-97 C; H NMR (300MHz, CDCl
3
, 22°C) δ
9
2
3
.00 (s, 1H), 7.92 (m, 2H), 7.85 (m, 6H), 7.64 (m, 4H), 7.54 (m, 6H), 7.45 (d, J = 7.8 Hz,
H), 7.39 (d, J = 10.9 Hz, 1H), 7.01 (d, J = 8.2 Hz, 1H), 6.35 (d, J = 12.1 Hz, 2H), 2.54 (s,
H) ppm.
O
6
-Methyl-2-phenyl chromen-4-one (5a):
suspension of 2-Benzoyloxy-5-methyl-benzoyl methyl
H C
3
A
O
triphenyl-phosphonium bromide (0.10 g, 0.17 mmol) in water (30
mL) and triethylamine (0.10 g, 1 mmol) was irradiated with a 150
5
a
W tungsten lamp (Philips India Ltd.) for 40 min. The reaction was monitored by TLC (after
10 minutes interval), and the product was isolated, after solvent extraction, by a column
o
filtration using a mixture of ethyl acetate and petroleum ether (60-80 C) (20% v/v) over silica
o
gel and crystallized from a mixture of acetone and petroleum ether (60-80 C) as colorless
o
1
o
shining flakes. Yield: 0.035 g (88%), mp 120-21 C, (lit. mp 122-23 C); IR (KBr) νmax 1645,
-
1 1
1
3
615, 1569, 1484, 1451, 1361 cm ; H NMR (300MHz, CDCl , 22°C): δ 8.04 (s, 1H), 7.96
(
dd, J = 6.5 Hz, 2.1 Hz, 2H), 7.52 (m, 5H), 7.06 (s, 1H), 2.45 (s, 3H) ppm.
1
3
C NMR (75 MHZ, CDCl , 22°C): δ 178.6, 163.6, 154.6, 135.4, 135.2, 131.8, 131.7, 129.1,
3
126.4, 125.0, 123.4, 117.9, 107.2, 21.0 ppm.
.+
Mass (EI), m/z (%): 237.0994 (M + H).
Similar procedures were followed for the preparation of esters (2b-2h & 7), bromo-esters
(
3b-3h), phosphonium salts (4b-4h & 9) and flavones (5b-5h & 10).
3

O
O
1-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-ethanone
(2b):
H C
3
o
Straw yellow crystalline granules, mp. 110-11 C (acetone-
CH3
o
petroleum ether) (60-80 C).
2b
2-Hydroxy-5-methyl acetophenone: 3g, 20 mmol; 4-
O
nitrobenzoic acid: 3.34 g, 20 mmol; SOCl : 3.57 g, 30 mmol;
2
NO2
Pyridine: 20 mL. Yield: 4.59g (77%).
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.36 (br s, 4H), 7.69 (s, 1H), 7.42 (d, J = 7.8 Hz, 1H),
7.13 (d, J = 8.1 Hz, 1H), 2.54 (s, 3H), 2.45 (s, 3H) ppm.
1
3
C NMR- APT- (75 MHZ, CDCl , 22°C): δ 197.3, 163.7, 150.9, 146.7, 136.5, 135.0, 134.3,
3
131.4, 131.1, 129.9, 123.7, 123.5, 29.1, 20.9 ppm.
O
1
-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-2-bromo ethanone
H C
3
Br
o
(3b): Straw yellow crystalline flakes, mp. 122-23 C (acetone-
o
O
petroleum ether) (60-80 C).
3
b
O
1-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-ethanone: 1.50 g, 5
mmol; bromine: 0.80 g, 5 mmol; glacial aceticacid: 15 mL.
NO2
yield: 1.23 g (65%).
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.35 (br s, 4H), 7.69 (s, 1H), 7.47 (d, J = 8.1 Hz, 1H),
7.19 (d, J = 8.1 Hz, 1H), 4.38 (s, 2H), 2.45 (s, 3H) ppm.
1
3
C NMR- APT- (75 MHZ, CDCl , 22°C): δ 190.4, 163.4, 150.9, 147.0, 136.6, 135.0, 134.6,
3
131.3, 131.28, 130.9, 123.8, 123.7, 33.0, 20.8 ppm.
O
2
-(4-Nitrobenzoyloxy)-5-methyl-benzoyl methyl triphenyl-
H C
3
PPh Br
3
phosphonium bromide (4b): Yellow crystalline granules, mp. >
o
O
250 C (dichloromethane-ethyl acetate).
4b
O
1-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-2-bromo ethanone:
NO2 0.38 g 1 mmol; triphenylphosphine: 0.26 g, 1 mmol. Yield:
0.39 g (61%).
1
H NMR (300MHz, CDCl , 22°C): δ 9.07 (s, 1H), 8.25 (m, 2H), 8.06 (d, J = 8.4 Hz, 2H),
3
7.85 (m, 5H), 7.69 (t, J = 6.6 Hz, 4H), 7.56 (br s, 6H), 7.43 (d, J = 8.1 Hz, 1H), 7.04 (d, J =
8
.1 Hz, 1H), 6.38 (d, J = 9.6 Hz, 2H), 2.54 (s, 3H) ppm.
1
3
3
C NMR- APT- (75 MHZ, CDCl , 22°C): 191.73, 191.7, 163.4, 150.8, 146.0, 138.2, 135.9,
135.1, 135.0, 134.7, 134.59, 134.6, 134.2, 134.1, 132.2, 132.1, 131.4, 131.3, 130.1, 130.0,
4

1
29.8, 129.7, 128.6, 128.5, 128.2, 128.1, 123.8, 123.7, 123.5, 123.4, 122.7, 119.3, 118.1,
1.9, 41.1, 20.8 ppm.
4
6
-Methyl-2-(4-nitro phenyl)-chromen-4-one (5b): Yellow
O
O
o
H C
3
crystalline flakes, mp. 274-75 C (acetone-petroleum ether)
o
2
o
(
60-80 C) (lit. mp 277 C).
5b
2-(4-Nitrobenzoyloxy)-5-methyl-benzoyl methyl triphenyl-
NO2
phosphonium bromide: 0.18 g, 0.27 mmol; Triethylamine:
o
0.1 g, 1 mmol; H
2
O: 20 mL; Eluent: ethyl acetate-petroleum ether (60-80 C) (30% v/v);
-
1
Yield: .0.06g (77%). IR (KBr) νmax 1640, 1617, 1523, 1484, 1343 cm .
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.38 (d, J = 8.7 Hz, 2H), 8.11 (d, J = 9.0 Hz, 2H), 8.03
(s, 1H), 7.54 (m, 2H), 6.89 (s, 1H), 2.49 (s, 3H), ppm.
O
O
1-[2-(4-Chlorobenzoyloxy)-5-methylphenyl]-ethanone
(2c):
H C
3
o
White crystalline granules, mp. 88-89 C (acetone-petroleum ether)
CH3
o
(
60-80 C).
2c
2-Hydroxy-5-methyl acetophenone: 1.50 g, 10 mmol; 4-
O
2
chlorobenzoic acid: 1.57 g, 10 mmol; SOCl : 2.38g, 20 mmol;
Cl
o
Pyridine: 20 mL. Eluent: ethyl acetate-petroleum ether (60-80 C) (10% v/v); Yield: 2.20g
(
76%).
1
H NMR (300MHz, CDCl , 22°C): δ 8.14 (m, 2H), 7.65 (d, J = 1.5 Hz, 1H), 7.50 (m, 2H),
3
6.39 (dd, J = 8.1 Hz, 1.8 Hz, 1H), 7.11 (d, J = 8.4 Hz, 1H), 2.52 (s, 3H), 2.43 (s, 3H) ppm.
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 197.5, 164.5, 147.0, 140.3, 136.1, 134.0, 131.6, 130.7,
129.0, 127.9, 123.6, 29.5, 20.8 ppm.
1
-[2-(4-Chlorobenzoyloxy)-5-methylphenyl]-2-bromo ethanone
O
O
o
H C
3
Br
(3c): White crystalline flakes, mp. 108-09 C (acetone-petroleum
o
ether) (60-80 C).
1-[2-(4-Chlorobenzoyloxy)-5-methylphenyl]-ethanone: 0.58 g, 2
3
c O
mmol; bromine: 0.32 g, 2 mmol; acetic acid: 15 mL. yield: 0.53 g
Cl
(
72%).
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.14 (m, 2H), 7.67 (d, J = 1.8 Hz, 1H), 7.51 (m, 2H),
7.44 (dd, J = 8.3 Hz, 2.0 Hz, 1H), 7.16 (d, J = 8.1 Hz, 1H), 4.37 (s, 2H), 2.44 (s, 3H) pm.
5

1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 190.8, 164.3, 147.3, 140.5, 136.4, 134.9, 131.7, 130.9,
129.1, 127.8, 127.6, 123.8, 33.8, 20.9 ppm.
2
-(4-Chlorobenzoyloxy)-5-methyl-benzoyl methyl triphenyl
O
O
H C
3
PPh Br
3
phosphonium bromide (4c): White crystalline granules, mp. 159-
o
60 C (dichloromethane-ethyl acetate).
4c
1-[2-(4-Chlorobenzoyloxy)-5-methylphenyl]-2-bromo
ethanone:
O
0.37 g, 1 mmol; triphenylphosphine: 0.26 g 1 mmol. Yield:
Cl
0.40 g (63%).
1
H NMR (300MHz, CDCl , 22°C): δ 8.99 (s, 1H), 7.82 (m, 8H), 7.64 (d, J = 6.9 Hz, 3H),
3
7
2
.53 (br s, 6H), 7.40 (d, J = 8.4 Hz, 3H), 6.99 (d, J = 8.1 Hz, 1H), 6.34 (d, J = 11.4 Hz, 2H),
.52 (s, 3H) ppm.
O
6-Methyl-2-(4-chlorophenyl)-chromen-4-one (5c): White
H C
3
o
crystalline needles, mp. 200-201 C (acetone-petroleum ether)
o
3
o
(
60-80 C) (lit. mp 198-99 C).
-(4-Chlorobenzoyloxy)-5-methyl-benzoyl methyl triphenyl-
O
5c
2
Cl
2
phosphonium bromide: 0.16 g, 0.25 mmol; Triethylamine: 0.1 g, 1 mmol; H O: 20 mL;
o
Eluent: ethyl acetate-petroleum ether (60-80 C) (15% v/v); Yield: .0.05g (73%); IR (KBr)
-
1
ν
max 1643, 1621, 1493, 1484, 1364 cm .
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.00 (s, 1H), 7.85 (dd, J = 7.7 Hz, 1.5 Hz, 2H), 7.48 (m,
4H), 6.77 (s, 1H), 2.46 (s, 3H) ppm.
1
3
C NMR- APT- (75 MHZ, CDCl
3
, 22°C): δ 178.4, 162.1, 154.5, 137.8, 135.4, 135.1, 130.4,
129.3, 127.5, 125.1, 123.6, 117.8, 107.6, 20.9 ppm.
O
O
1-[2-(Benzoyloxy)-phenyl]-ethanone (2d): White crystalline granules,
o
o
CH3
mp. 87-88 C (dichloromethane-petroleum ether) (60-80 C).
Ortho hydroxy acetophenone: 4.08 g, 30 mmol; Benzoyl chloride: 4.20 g,
2d
O
30 mmol; dry pyridine: 30mL; Yield: 6.10g (85%).
1
H NMR (300MHz, CDCl , 22°C): δ 8.22 (d, J = 8.1 Hz, 2H), 7.87 (d, J =
3
7.8 Hz, 1H), 7.65 (m, 1H), 7.55 (q, J = 8.5 Hz, 3H), 7.37 (t, J = 7.5 Hz, 1H), 7.24 (d, J = 8.1
Hz, 1H), 2.56 (s, 3H) ppm.
6

O
O
1-[2-(Benzoyloxy)-phenyl]-2-bromo ethanone (3d): White crystalline
Br
o
o
granules, mp. 74-75 C (dichloromethane-petroleum ether) (60-80 C).
1-[2-(Benzoyloxy)-phenyl]-ethanone: 2.40 g, 10 mmol; bromine: 1.60 g,
3d
O
10mmol; acetic acid: 25 mL. yield: 2.20 g (69%).
1
H NMR (300MHz, CDCl , 22°C): δ 8.23 (d, J = 7.8 Hz, 2H), 7.90 (d, J =
3
7.8 Hz, 1H), 7.67 (m, 2H), 7.55 (t, J = 7.7 Hz, 2H), 7.41 (t, J = 7.5 Hz, 1H), 7.32 (d, J = 8.1
Hz, 1H), 4.42 (s, 2H) ppm.
O
O
2-(Benzoyloxy)-benzoyl methyl triphenyl phosphonium bromide
PPh Br
3
o
(
4d): White crystalline granules, mp. 204-06 C (dichloromethane-ethyl
acetate).
4d
O
1-[2-(Benzoyloxy)-phenyl]-2-bromo ethanone: 3.20 g, 10 mmol;
triphenyl phosphine: 2.62 g, 10 mmol. Yield: 4.30 g (74%).
1
H NMR (300MHz, CDCl
d, J = 8.1 Hz, 3H), 7.75 (d, J = 8.1 Hz, 3H), 7.59 (m, 4H), 7.48 (m, 7H), 7.40 (t, J = 7.7, 3H)
.08 (d, J = 7.8 Hz, 1H), 6.28 (d, J = 12.0 Hz, 2H) ppm.
3
, 22°C): δ 8.98 (d, J = 7.8 Hz, 1H), 7.85 (d, J = 8.1 Hz, 2H), 7.80
(
7
o
O
2-phenyl chromen-4-one (5d): White crystalline flakes, mp.97-98 C
o
4
o
(
acetone-petroleum ether) (60-80 C) (lit. mp 96 C).
O
2-(Benzoyloxy)-benzoyl methyl triphenyl phosphonium bromide: 0.58
5
d
2
g, 1 mmol; Triethylamine: 0.4 g, 4 mmol; H O: 25 mL; Eluent: ethyl
o
acetate-petroleum ether (60-80 C) (20% v/v); Yield: 0.19 g (86%). IR (KBr) νmax 1646, 1605,
-
1
1
569, 1466, 1450, 1376 cm .
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.23 (d, J = 7.8 Hz, 1H), 7.92 (dd, J = 6.2 Hz, 2.7 Hz,
2H), 7.70 (t, J = 7.2 Hz, 1H), 7.54 (m, 4H), 7.42 (t, J = 7.5 Hz, 1H), 6.85 (s, 1H) ppm.
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 178.5, 163.6, 156.3, 133.9, 131.7, 131.7, 129.1, 126.4,
125.7, 125.3, 123.9, 118.1, 107.5 ppm.
1
-[2-(4-Nitrobenzoyloxy)-phenyl]-ethanone (2e): Straw yellow cry-
O
O
o
o
stallline granules, mp. 95-96 C (acetone-petroleum ether) (60-80 C).
CH3
Ortho hydroxy acetophenone: 2.72 g, 20 mmol; 4-nitrobenzoic acid:
2
e
3
.34 g, 20 mmol; SOCl
2
: 3.57g, 30 mmol; Pyridine: 20 mL. Yield:
O
3.85g (68%).
NO2
7

1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.35 (m, 4H), 7.90 (dd, J = 7.8 Hz, 1.5 Hz, 1H), 7.62
(dt, J = 7.8 Hz, 1.5 Hz, 1H), 7.42 (dt, J = 7.7 Hz, 1.1 Hz, 1H), 7.25 (dd, J = 8.1 Hz, 0.9 Hz,
1H), 2.55 (s, 3H) ppm.
1
3
C NMR (75 MHZ, CDCl , 22°C): δ 197.2, 163.5, 150.8, 148.8, 134.9, 133.7, 131.4, 130.7,
3
130.2, 126.6, 123.8, 123.7, 29.0 ppm.
1
-[2-(4-Nitrobenzoyloxy)-phenyl]-2-bromo ethanone (3e): Straw
O
O
o
Br
yellow crystalline flakes, mp. 94-95 C (acetone-petroleum ether) (60-
o
80 C).
3e
1
-[2-(4-Nitrobenzoyloxy)-phenyl]-ethanone: 1.43 g 5 mmol; bromine:
.80 g 5 mmol; glacial acetic acid: 15 mL. yield: 1.00 g (55%).
O
0
NO2
1
H NMR (300MHz, CDCl , 22°C): δ 8.37 (br s, 4H), 7.92 (d, J = 7.5
3
Hz, 1H), 7.68 (t, J = 7.4 Hz, 1H), 7.45 (t, J = 7.4 Hz, 1H), 7.32 (d, J = 8.1 Hz, 1H), 4.39 (s,
2
H) ppm.
1
3
C NMR (75 MHZ,CDCl , 22°C): δ 190.3, 163.3, 151.0, 149.4, 134.5, 131.4, 130.6, 127.4,
3
126.7, 124.2, 123.8, 32.9 ppm.
O
2
-(4-Nitrobenzoyloxy)-phenyl)-benzoyl
methyl
triphenyl
PPh Br
3
o
phosphonium bromide (4e): yellow crystalline solid, mp. 154 C
(dec) (dichloromethane-ethyl acetate).
O
4e
O
1-[2-(4-Nitrobenzoyloxy)-phenyl]-2-bromo ethanone: 0.55 g 1.5
NO2 mmol; triphenylphosphine: 0.39 g 1.5 mmol; toluene: 20ml; Yield:
0.63 g (67%).
1
H NMR (300MHz, CDCl , 22°C): δ 9.12 (s, 1H), 8.27 (d, J = 8.4 Hz, 2H), 8.06 (d, J = 8.5
3
Hz, 3H), 7.85 (m, 4H), 7.63 (m, 12H), 7.16 (d, J = 7.6 Hz, 1H), 6.46 (d, J = 11.1 Hz, 2H)
ppm.
O
O
2-(4-Nitro phenyl)-chromen-4-one (5e): White crystalline solid,
o
o
4
mp 239-40 C (acetone-petroleum ether) (60-80 C) (lit. mp 242-
o
4
4 C).
5e
2-(4-Nitrobenzoyloxy)-phenyl)-benzoyl
methyl
triphenyl
NO2
phosphonium bromide: 0.31 g, 0.5 mmol; Triethylamine: 0.2 g, 2 mmol; H
2
O: 25 mL; Eluent:
o
ethyl acetate-petroleum ether (60-80 C) (30% v/v); Yield: 0.09 g (69%). IR (KBr) νmax 1660,
-
1
1
610, 1520, 1468, 1417, 1346 cm .
8

1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.40 (d, J = 8.7 Hz, 2H), 8.25 (d, J = 7.8 Hz, 1H), 8.12
(
d, J = 8.7 Hz, 2H), 7.76 (t, J = 7.7 Hz, 1H), 7.61 (d, J = 8.1 Hz, 1H), 7.48 (t, J = 7.5 Hz, 1H),
6
.92 (s, 1H) ppm.
1
-[2-(4-Chlorobenzoyloxy)-phenyl]-ethanone (2f): White crystalline
O
o
o
granules, mp. 90-91 C (acetone-petroleum ether) (60-80 C).
CH3
Ortho hydroxy acetophenone: 4.08 g, 30 mmol; 4-chlorobenzoic acid:
O
2f
4
.7 g, 30 mmol; SOCl
78%).
H NMR (300MHz, CDCl , 22°C): δ 8.14 (d, J = 8.1 Hz, 2H), 7.86 (d, J = 7.8 Hz, 1H), 7.58
t, J = 7.7 Hz, 1H), 7.49 (d, J = 8.1 Hz, 2H), 7.37 (t, J = 7.5 Hz, 1H), 7.24 (d, J = 7.8 Hz, 1H),
2
: 5.4 g, 45 mmol; Pyridine: 30 mL. Yield: 6.4 g
O
(
Cl
1
3
(
2
.53 (s, 3H) ppm.
1
3
C NMR (75 MHZ, CDCl , 22°C): δ 197.3, 164.3, 149.1, 140.2, 133.4, 131.6, 130.9, 130.3,
3
129.0, 127.8, 126.2, 123.8, 29.4 ppm.
1
-[2-(4-Chlorobenzoyloxy)-phenyl]-2-bromo ethanone (3f): White
O
O
Br
o
o
crystalline flakes, mp. 68-70 C (acetone-petroleum ether) (60-80 C).
-[2-(4-Chlorobenzoyloxy)-phenyl]-ethanone: 2.75 g, 10 mmol;
bromine: 1.60 g, 10 mmol; glacial acetic acid: 20 mL. yield: 1.90g
54%).
H NMR (300MHz, CDCl , 22°C): δ 8.15 (d, J = 8.4 Hz, 2H), 7.89 (d, J = 7.8 Hz, 1H), 7.65
t, J = 7.2 Hz, 1H), 7.52 (d, J = 8.4 Hz, 2H), 7.42 (t, J = 7.5 Hz, 1H), 7.29 (d, J = 8.1 Hz, 1H),
1
3
f
O
(
Cl
1
3
(
4
.38 (s, 2H) ppm.
1
3
C NMR (75 MHZ, CDCl , 22°C): δ 190.5, 164.0, 149.4, 140.5, 134.2, 131.6, 130.5, 129.1,
3
128.1, 127.4, 126.3, 124.1, 33.5 ppm.
O
O
2-(4-Chlorobenzoyloxy)-phenyl)-benzoyl
methyl
triphenyl
PPh Br
o
3
phosphonium bromide (4f): White crystalline granules, mp. 163-65 C
(
dichloromethane-ethyl acetate).
-[2-(4-Chlorobenzoyloxy)-phenyl]-2-bromo ethanone: 0.35 g, 1 mmol;
triphenylphosphine: 0.26 g, 1 mmol. Yield: 0.39 g (64%).
4f
1
O
Cl
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.97 (d, J = 7.5, 1H), 7.78 (m, 8H), 7.61 (m, 3H), 7.47
(
m, 8H), 7.37 (d, J = 8.4, 2H), 7.08 (d, J = 7.8, 1H), 6.29 (d, J = 12.3, 2H) ppm.
9

1
3
C NMR (75 MHZ, CDCl , 22°C): δ 191.4, 191.3, 164.0, 148.2, 140.0, 134.8, 134.5, 134.4,
3
1
33.9, 133.8, 132.7, 131.5, 129.9, 129.8, 129.1, 129.0, 128.6, 127.3, 127.0, 123.1, 129.0,
17.8, 41.0, 40.2.
1
2
-(4-Chlorophenyl)-chromen-4-one (5f): White crystalline needles,
O
o
o
4
mp. 186-87 C (acetone- petroleum ether) (60-80 C) (lit. mp 186-
o
8
8 C).
O
5
f
2-(4-Chlorobenzoyloxy)-phenyl)-benzoyl
methyl
triphenyl
Cl
phosphonium bromide: 0.11 g, 0.18 mmol; Triethylamine: 0.1 g, 1 mmol; H
2
O: 20 mL;
o
Eluent: ethyl acetate-petroleum ether (60-80 C) (15% v/v); Yield: 0.04g (87%). IR (KBr) νmax
-
1
1
662, 1643, 1606, 1467, 1408, 1375 cm .
1
H NMR (300MHz, CDCl
t, J = 7.4 Hz, 1H), 7.57 (d, J = 8.4 Hz, 1H), 7.51 (d, J = 8.4 Hz, 2H), 7.44 (t, J = 7.5 Hz, 1H),
.83 (s, 1H) ppm.
3
, 22°C): δ 8.23 (d, J = 7.8 Hz, 1H), 7.87 (d, J = 8.4 Hz, 2H), 7.72
(
6
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 178.3, 162.4, 156.2, 138.0, 134.0, 130.2, 129.4, 127.6,
125.8, 125. 5, 123. 8, 118.0, 107.6 ppm.
O
O
1-(2-Benzoyloxy-5-chlorophenyl)-ethanone (2g): Colorless crystal-
Cl
o
o
line granules, mp. 70-71 C (acetone-petroleum ether) (60-80 C).
CH3
2
-Hydroxy-5-chloro acetophenone: 3.41 g, 20 mmol; benzoyl chloride:
.81 g, 20 mmol; Pyridine: 30 mL. Yield: 4.91 g (89%).
2g
2
O
1
H NMR (300MHz, CDCl , 22°C): δ 8.19 (m, 2H), 7.81 (d, J = 2.6 Hz,
3
1H), 7.65 (m, 1H), 7.53 (m, 3H), 7.19 (d, J = 8.6 Hz, 1H), 2.52 (s, 3H) ppm.
1
-(2-Benzoyloxy-5-chlorophenyl)-2-bromo ethanone (3g): Colorless
O
O
Cl
Br
o
o
crystalline flakes, mp. 82-83 C (acetone-petroleum ether) (60-80 C).
1-(2-Benzoyloxy-5-chlorophenyl)-ethanone: 1.10 g, 4 mmol; bromine:
3
g
0.64 g, 4 mmol; glacial acetic acid: 20 mL. yield: 0.95g (67%).
O
1
H NMR (300MHz, CDCl , 22°C): δ 8.19 (d, J = 7.5 Hz, 2H), 7.85 (d,
3
J = 2.4 Hz, 1H), 7.69 (t, J = 7.4 Hz, 1H), 7.57 (m, 3H), 7.26 (d, J = 8.7 Hz, 1H), 4.36 (s, 2H)
ppm.
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 189.8, 164.5, 147.9, 134.3, 133.8, 131.9, 130.3, 129.7,
128.9, 128.6, 125.5, 33.7 ppm.
10

2
-Benzoyloxy-5-chloro-benzoyl
methyl
triphenyl
O
O
Cl
PPh Br
3
phosphonium bromide (4g): White crystalline granules, mp.
o
1
1
81-83 C (dichloromethane-ethyl acetate).
-(2-Benzoyloxy-5-chlorophenyl)-2-bromo ethanone: 0.71 g, 2
4g
O
mmol; triphenyl phosphine: 0.52 g 2 mmol. Yield: 0.89 g (72%).
1
H NMR (300MHz, CDCl , 22°C): δ 9.04 (s, 1H), 7.91 (d, J =
3
7.9 Hz, 2H), 7.80 (m, 6H), 7.62 (d, J = 5.3 Hz, 4H), 7.48 (m, 9H), 7.07 (d, J = 8.6 Hz, 1H),
-
1
6
.41 (d, J = 12.1 Hz, 2H) ppm. IR (KBr) νmax 1662, 1643, 1606, 1467, 1408, 1375 cm .
6
-Chloro-2-phenyl chromen-4-one (5g): White crystalline
O
O
o
o
1
needles, mp. 185-186 C (acetone- petroleum ether) (60-80 C) (lit.
Cl
o
mp 184-85 C).
2-Benzoyloxy-5-chloro-benzoyl methyl triphenyl phosphonium
5
g
2
bromide: 0.31 g, 0.5 mmol; Triethyl amine: 0.5 g, 5 mmol; H O: 20
o
mL; Eluent: ethyl acetate-petroleum ether (60-80 C) (20% v/v); Yield: .0.12 g (91%). IR
-
1
(
KBr) νmax 1648, 1602, 1566, 1458, 1438, 1354 cm .
1
H NMR (300MHz, CDCl , 22°C): δ 8.20 (d, J = 2.5 Hz, 1H), 7.92 (m, 2H), 7.65 (dd, J = 9.0
3
Hz, 2.6 Hz, 2H),, 7.53 (m, 4H), 6.83 (s, 1H) ppm.
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 177.2, 163.7, 154.6, 134.0, 131.8, 131.4, 131.2, 129.1,
126.3, 125.2, 124.9, 119.8, 107.5 ppm.
1
-(2-Benzoyloxy-5-methoxyphenyl)-ethanone
(2h):
Colorless
O
O
liquid.1-(2-Hydroxy-4-methoxy phenyl)-ethanone: 1.66 g, 10 mmol;
Benzoyl chloride: 1.4 g, 10 mmol; Pyridine: 20 mL; Eluent: ethyl
CH3
MeO
o
acetate and petroleum ether (60-80 C) (20% v/v), Yield: 2.2 g (81%).
O
1
2h
3
H NMR (300MHz, CDCl , 22°C): δ 8.22 (d, J = 7.9 Hz, 2H), 7.89 (d,
J = 8.8 Hz, 1H), 7.65 (t, J = 6.9 Hz, 1H), 7.55 (t, J = 7.5 Hz, 2H), 6.87 (d, J = 8.8 Hz, 1H),
6.73 (s, 1H), 3.86 (s, 3H), 2.49 (s, 3H) ppm.
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 195.7, 165.1, 163.8, 151.7, 133.8, 132.4, 130.3, 129.4,
128.7, 123.6, 112.0, 109.3, 55.7, 29.5 ppm.
11

O
O
1-[2-Benzoyloxy-4-methoxy-5-bromo-phenyl]–2–bromo-ethanone
3h): Colorless sticky liquid.
-(2-Benzoyloxy-5-methoxyphenyl)-ethanone: 2.70 g, 10 mmol;
Bromine: 1.60 g, 10 mmol; glacial acetic acid: 20 mL; yield: 2.98 g
70%).
Br
Br
(
1
MeO
3h
O
(
2
-Benzoyloxy-4-methoxy-5-bromo-benzoyl methyl triphenyl
O
Br
PPh Br
3
phosphonium bromide (4h): White crystalline granules, mp. 197-
o
9
8 C (dec) (dichloromethane-ethyl acetate).1-[2-Benzoyloxy-4-
MeO
O
4h
methoxy-5-bromo-phenyl]–2–bromo-ethanone: 0.60 g, 2 mmol;
triphenylphosphine : 0.52 g 2 mmol. Yield: 0.59 g (56%).
O
O
O
6-Bromo-7-methoxy-2-phenyl-chromene-4-one (5h): White
Br
MeO
o
crystalline needles, mp. 191-92 C (dec) (acetone-petroleum
o
ether, 60-80 C).
5h
2-Benzoyloxy-4-methoxy-5-bromo-benzoyl methyl triphenyl
2
phosphonium bromide : 0.35 g 0.5 mmol; Triethylamine: .5 g, 5 mmol; H O: 20 mL; Eluent:
o
ethyl acetate-petroleum ether (60-80 C) (20% v/v); Yield: .0.1g (63%). IR (KBr) νmax 1637,
-
1
1
597, 1452, 1430, 1358 cm .
1
H NMR (500MHz, CDCl
3
, 22°C): δ 8.41 (s, 1H), 7.90 (m, 2H), 7.53 (m, 3H), 7.00 (s, 1H),
6.78 (s, 1H), 4.03 (s, 3H) ppm.
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 176.6, 163.3, 160.1, 156.9, 131.6, 130.1, 129.1, 126.2,
118.6, 110.1, 107.6, 100.1, 56.9 ppm.
The crystal structure has been deposited at the Cambridge Crystallographic Data Centre and
allocated the deposition number CCDC 838053.
1-(2,4-Dihydroxy-5-acetylphenyl)-ethanone (6):
O
O
o
colourless crystalline needles, mp 178-79 C (petroleum ether, 60-
H C
3
CH3
o
8
0 C).
HO
OH
6
A mixture of freshly prepared fused zinc chloride (10.1 g, 100 mmol)
and resorcinol (5.5g, 50 mmol) in dry acetic anhydride (15.3 g, 150 mmol) are taken in a
o
round-bottom flask and heated gently in an oil bath to 142 C for 15 min with the help of a
magnetic stirrer. The reaction mixture was allowed to cool at room temperature and a syrupy
mass was obtained. After then 150 gm crushed ice and conc HCl (80mL) was added to it and
12

stirred for 30 min, an orange red color crystalline material separated out. The crude product
o
crystallized from petroleum ether (60-80 C) to give the expected product as colorless
1
crystalline needles. Yield: .5.9 g (61%); H NMR (300MHz, CDCl
3
, 22°C): δ 12.91 (s, 2H),
8.18 (s, 1H), 6.38 (s, 1H), 2.61 (s, 6H) ppm.
1
3
C NMR (75 MHZ, CDCl , 22°C): δ 202.4, 168.8, 136.2, 113.6, 104.9, 26.0 ppm.
3
O
O
O
O
1
-(2,4-Dibenzoyloxy-5-acetylphenyl)-ethanone (7): colourless
o
H C
3
CH3
crystalline granules, mp 118-19 C (acetone-petroleum ether, 60-
o
80 C).
O
O
1-(2,4-Dihydroxy-5-acetylphenyl)-ethanone: 1.94 g, 10 mmol;
Benzoyl chloride: 2.81 g, 20 mmol; dry pyridine: 30 mL; Yield:
7
2.90 g (72%).
1
H NMR (300MHz, CDCl
3
, 22°C): δ 8.41 (s, 1H), 8.20 (dd, J = 8.0 Hz, 1.5 Hz, 4H), 7.67 (m,
2H), 7.54 (t, J = 7.7 Hz, 4H), 7.25 (s, 1H), 2.60 (s, 6H),ppm.
1
3
C NMR (75 MHZ, CDCl
3
, 22°C): δ 195.6, 164.3, 152.7, 134.2, 132.6, 130.4, 129.0, 128.8,
128.5, 119.8, 29.8 ppm.
O
O
O
O
1-[2,4–Dibenzoyloxy–5-(2-bromoacetyl)-phenyl]–2–bromo-
ethanone (8): 1-(2,4-Dibenzoyloxy-5-acetylphenyl)-ethanone
(1.05g, 2.50 mmol) and acetic acid (25 mL) was taken in a 100
mL round-bottomed flask and bromine (0.8 g, 5 mmol) added to
it, and the hole reaction mixture was heated gently until the read
Br
Br
O
O
8
color of the reaction mixtire turned to colorless or straw yellow. It was then cooled at room
temperature and 150 g crushed icc added to it. A sticky semi solid mass was so obtained after
1
solvent extraction.Yield: .0.95 g (65%). H NMR (300MHz, CDCl
3
, 22°C): δ 8.42 (d, J = 10.2
Hz, 1H), 8.16 (d, J = 7.6 Hz, 4H), 7.65 (t, J = 7.0 Hz, 2H) 7.51 (t, J = 7.5 Hz, 4H) 7.38 (s,
1H) 4.43 (s, 4H) ppm.
2
, 4-Dibenzoyloxy-5-(2-oxoethyltriphenylphosphonium)-
O
O
O
O
BrPh3P
PPh Br
3
benzoyl methyl triphenyl phosphonium dibromide (9):
o
colourless
crystalline
granules,
mp
>
270 C
(
dichloromethane-ethyl acetate).
O
O
9
13

1-[2,4–Dibenzoyloxy–5-(2-bromoacetyl)-phenyl]–2–bromoethanone: 0.56 g,
1
mmol;
triphenylphosphine: 0.52 g, 2 mmol. Yield: 0.77 g (71%).
2
, 8-Diphenyl-pyrano [3, 2-g] chromene-4, 6-dione (10):
O
O
O
O
o
colourless crystalline needles, mp 268-69 C (acetone-
o
petroleum ether, 60-80 C).
10
2,
4-Dibenzoyloxy-5-(2-oxoethyltriphenylphosphonium)-
benzoyl methyl triphenyl phosphonium dibromide: 0.22 g, 0.20 mmol; Triethylamine: 1.01 g,
o
1
0 mmol; H
2
O: 40 mL; Eluent: ethyl acetate-petroleum ether (60-80 C) (30% v/v); Yield:
-
1
0
.053g (72%). IR (KBr) νmax 1646, 1609, 1450, 1467, 1366, cm .
1
H NMR (300MHz, CDCl , 22°C): δ 9.14 (s, 1H), 7.95 (m, 4H), 7.73 (s, 1H), 7.57 (d, J = 6.1
3
Hz, 6H), 6.85 (s, 2H) ppm.
1
3
C NMR (75 MHZ, CDCl
21.7, 107.5, 106.4, ppm.
3
, 22°C): δ 177.2, 163.8, 158.6, 132.0, 131.2, 129.2, 126.3, 126.1,
1
.
+
Mass (EI), m/z (%): 389.13 (M + Na).
References:
1.
Bennardi, D.; Romanelli, G.; Autino, J.; Pizzio, L.; Vazquez, P.; Caceres, C.; Blanco,
M. Reac Kinet Mech Cat 2010, 100, 165-174.
2.
Sarada, S. R.; Pathan, M. Y.; Paike, V. V.; Pachmase, P. R.; Jadhav, W. N.; Pawar, R.
P. Arkivoc. 2006, (XVI), 43-48.
3
.
.
Sing, O. V.; Muthukrishnan, M.; Raj, G. Synth. Commun. 2005, 35, 2723–2728.
Kumar, P.; Bodas, M. S. Org. Lett. 2000, 2, 3821-3823.
4
14

1
Fig. 1: H NMR spectrum of 1-(2-Benzoyloxy-5-methylphenyl)-ethanone (2a)
15

1
Fig. 2: H NMR spectrum of 1-(2-Benzoyloxy-5-methylphenyl)-2-bromo ethanone (3a)
16

1
3
Fig. 3: C NMR spectrum of 1-(2-Benzoyloxy-5-methylphenyl)-2-bromo ethanone (3a)
17

1
Fig. 4: H NMR spectrum of 2-Benzoyloxy-5-methyl-benzoyl methyl triphenyl
phosphonium bromide (4a)
18

1
Fig. 5: H NMR spectrum of 6-Methyl-2-phenyl chromen-4-one (5a)
19

1
3
Fig. 6: C NMR spectrum of 6-Methyl-2-phenyl chromen-4-one (5a)
20

Fig 7: High Resolution Mass spectrum of 6-Methyl-2-phenyl chromen-4-one (5a):
21

1
Fig 8: H NMR spectrum of 1-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-ethanone (2b)
22

1
3
Fig. 9: C NMR spectrum of 1-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-ethanone (2b)
23

1
Fig. 10: H NMR spectrum of 1-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-2-bromo
ethanone (3b)
24

1
3
Fig. 11: C NMR spectrum of 1-[2-(4-Nitrobenzoyloxy)-5-methylphenyl]-2-bromo
ethanone (3b)
25

1
Fig. 12: H NMR spectrum of 2-(4-Nitrobenzoyloxy)-5-methyl-benzoyl methyl triphenyl
phosphonium bromide (4b)
26

1
3
Fig. 13: C NMR spectrum of 2-(4-Nitrobenzoyloxy)-5-methyl-benzoyl methyl triphenyl
phosphonium bromide (4b)
27

1
Fig. 14: H NMR spectrum of 6-Methyl-2-(4-nitro phenyl)-chromen-4-one (5b)
28

1
Fig. 15: H NMR spectrum of 1-[2-(4-Chlorobenzoyloxy)-5-methylphenyl]-ethanone (2c)
29

1
3
Fig. 16: C NMR spectrum of 1-[2-(4-Chlorobenzoyloxy)-5-methylphenyl]-ethanone
2c)
(
30