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1694, 1665, 1598, 1584, 1550, 1492, 1469, 1447, 1383, 1285, 1247,
1157, 1130, 1030 cm–1. HRMS (ESI): m/z calcd. for C15H10OCl2 + H+ (s,
[M + H]+ 277.0187; found 277.0174.
2 H, ArH), 6.52 (d, J = 8.2 Hz, 1 H, =CH), 3.93 (s, 3 H, ArOCH3), 3.90
3
H, ArOCH3), 3.84 (s, 6 H, 2 × ArOCH3), 3.81 (s, 6 H,
2 × ArOCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 193.5 (CHO), 162.1
(C), 153.3 (C), 153.1 (C), 140.6 (C), 139.3 (C), 134.8 (C), 132.0 (C),
126.8 (C), 108.4 (CH), 106.4 (CH), 61.2 (ArOCH3), 61.1 (ArOCH3), 56.4
Compound 9d: Yield 0.3 g (62 %, over two steps); yellow gummy
solid; Rf = 0.56 (EtOAc/hexanes, 1:9); mixture of geometrical isomer
(ca. 1.1:1). H NMR (400 MHz, CDCl3): δ = 9.59 (d, J = 7.6 Hz, minor
CHO), 9.46 (d, J = 8.0 Hz, 1 H, major CHO), 8.02 (s, 1 H, ArH), 7.93
(s, 1 H, ArH), 7.78 (s, 4 H, ArH), 7.58–7.47 (m, 4 H, ArH), 7.46–7.41
(m, 2 H, ArH), 7.31–7.29 (m, 4 H, ArH), 6.73 (d, J = 8.0 Hz, 1 H, =CH),
6.61 (d, J = 7.6 Hz, 1 H, =CH) ppm. 13C NMR (100 MHz, CDCl3): δ =
192.6 (CHO), 191.5 (CHO), 158.5, 158.3, 142.3, 139.0, 138.2, 135.1,
132.6, 132.5, 132.26, 132.20, 131.4, 130.7, 130.5, 130.4, 129.5, 129.3,
129.1, 128.7, 128.53, 128.50, 128.46, 124.41, 123.89, 123.85, 123.45,
(ArOCH3), 56.4 (ArOCH3) ppm. IR (CHCl3): νmax = 2966, 2939, 2840,
˜
1
1655, 1580, 1505, 1463, 1431, 1414, 1360, 1327, 1239, 1186, 1169,
1129 cm–1. HRMS (ESI): m/z calcd. for C21H24O7 + H+ [M + H]+
389.1600; found 389.1581.
General Procedure for Synthesis of 3,3-Diarylacrylic Acid 8:
Oxidation of acroleins 9 were performed by using a reported proce-
dure[14] with some modifications. Compound 9m (0.50 g,
2.05 mmol) was dissolved in dimethyl sulfoxide (15 mL) and aq.
NaH2PO4·2H2O (0.1 mL, 80 mg, 0.51 mmol) was added, followed by
aq. NaClO2 (3.6 mL, 0.45 g, 4.93 mmol) slowly over a period of 3 h
and the mixture was stirred for 6 h at room temp. After complete
consumption of starting material as revealed by TLC, the reaction
medium was acidified with aq. 20 % HCl to pH ca. 2–3 and the
aqueous layer was extracted with EtOAc (3 × 15 mL). The organic
layers were collected, dried with anhydrous Na2SO4, concentrated
and purified by silica-gel column chromatography (EtOAc/hexanes,
6:4) to give 8m, yield 0.47 g (88 %); colourless crystalline solid;[5b]
Rf = 0.28 (EtOAc/hexanes, 2:8). 1H NMR (400 MHz, CDCl3): δ = 7.19–
7.14 (m, 2 H, ArH), 7.11–7.07 (m, 2 H, ArH), 7.00–6.92 (m, 4 H, ArH),
6.16 (s, 1 H, =CH) ppm. 13C NMR (100 MHz, CDCl3): δ = 170.7
(COOH), 165.2 (C), 164.3 (C), 162.7 (C), 161.8 (C), 157.2 (C), 136.9 (C),
136.8 (C), 134.16 (C), 134.13 (C), 131.38 (CH), 131.30 (CH), 130.6 (CH),
130.5 (CH), 116.4 (CH), 115.8 (CH), 115.6 (CH), 115.3 (CH), 115.1
123.42, 123.3, 121.7, 121.6 ppm. IR (CHCl3): νmax = 1727, 1671, 1613,
˜
1379, 1215, 1185, 1143, 1109, 904 cm–1. HRMS (ESI): m/z calcd. for
C17H10OF6 + H+ [M + H]+ 345.0714; found 345.0699.
Compound 9e: Yield 0.51 g (73 %, over two steps); yellow gummy
solid; Rf = 0.50 (EtOAc/hexanes, 1:9); mixture of geometrical isomer
1
(ca. 1.5:1). H NMR (400 MHz, CDCl3): δ = 9.54 (t, J = 8.4 Hz, 1.6 H,
CHO), 7.51–7.45 (m, 3 H, ArH), 7.44–7.38 (m, 2 H, ArH), 7.35–7.32 (m,
2 H, ArH), 7.30–7.28 (m, 1 H, ArH), 6.97–6.92 (m, 1 H, ArH), 6.90–6.84
(m, 4 H, ArH), 6.61 (d, J = 8.0 Hz, 1 H, major =CH), 6.54 (d, J = 7.6 Hz,
minor =CH) ppm. 13C NMR (100 MHz, CDCl3): δ = 193.0 (CHO), 192.4
(CHO), 164.3 (C), 164.2 (C), 164.1 (C), 161.7 (C), 161.6 (C), 159.2 (C),
139.9 (C), 138.4 (C), 135.5 (C), 131.1 (CH), 130.7 (CH), 130.0 (CH),
129.0 (CH), 128.8 (CH), 128.5 (CH), 128.4 (CH), 127.9 (CH), 113.9 (CH),
113.8 (CH), 113.7 (CH), 113.6 (CH), 111.79 (CH), 111.7 (CH), 111.6
(CH), 111.5 (CH), 105.9 (CH), 105.7 (CH), 105.4 (CH), 105.2 (CH), 105.0
(CH) ppm. IR (CHCl ): ν
= 2926, 2854, 1701, 1671, 1602, 1526,
˜
3
max
(CH), 104.7 (CH) ppm. IR (CHCl3): νmax = 1723, 1701, 1667, 1620,
1447, 1379, 1326, 1280, 1182, 1140 cm–1
.
˜
1593, 1512, 1435, 1349, 1325, 1122 cm–1. HRMS (ESI): m/z calcd. for
General Procedure for the Preparation of 3,3-Diarylpropanoic
Acid 7: To a solution of 8a (0.74 g, 3.32 mmol) in ethyl acetate
(15 mL), 10 % Pd/C (0.18 g, 0.16 mmol), was added and the mixture
was stirred at room temp. under a H2 balloon (for compound 8i, 8j
and 8k, a H2 pressure of 50–60 psi was required for up to 6–8 h)
and within 3–4 h the reaction was complete. The reaction mixture
was filtered through Celite, washed with EtOAc (3 × 3 mL) and con-
centrated under reduced pressure to afford 7a, which was pure
enough to be carried forward without any further purification for
the next step, yield 0.71 g (94 %); colourless solid;[18] m.p. 140–
142 °C; Rf = 0.3 (EtOAc/hexanes, 2:8). 1H NMR (400 MHz, CDCl3): δ =
7.21–7.15 (m, 5 H, ArH), 7.13–7.09 (m, 5 H, ArH), 4.44 (t, J = 8.0 Hz,
1 H, CHCH2), 3.00 (d, J = 8.0 Hz, CH2) ppm. 13C NMR (100 MHz,
CDCl3): δ = 177.4 (COOH), 143.3 (ArC), 128.7 (ArCH), 127.7 (ArCH),
C
15H10OF2 + H+ [M + H]+ 245.0778; found 245.0785.
Compound 9f: Yield 0.44 g (72 %, over two steps); yellowish vis-
cous liquid; Rf = 0.27 (EtOAc/hexanes, 0.5:0.95); mixture of geometri-
cal isomers (ca. 1.5:1). 1H NMR (400 MHz, CDCl3): δ = 9.54 (t, J =
8.4 Hz, major and minor CHO), 7.51–7.38 (m, 5 H, ArH), 7.35–7.27
(m, 3 H, ArH), 6.97–6.92 (m, 1 H, ArH), 6.90–6.84 (m, 4 H, ArH), 6.61
(d, J = 8.0 Hz, 1 H, major =CH), 6.54 (d, J = 8.0 Hz, minor =CH) ppm.
13C NMR (100 MHz, CDCl3): δ = 193.0 (CHO), 192.4 (CHO), 164.4,
164.2, 164.1, 161.9, 161.7, 161.6, 159.2, 139.9, 138.4, 135.5, 131.1,
130.7, 130.0, 129.0, 128.8, 128.5, 128.4, 127.9, 113.9, 113.8, 113.77,
113.70, 111.79, 111.72, 111.6, 111.5, 105.9, 105.7, 105.4, 105.2, 105.0,
104.7 ppm. IR (CHCl3): νmax = 2851, 1669, 1620, 1590, 1434, 1390,
˜
1354, 1122, 991, 928, 880, 855, 668 cm–1. HRMS (ESI): m/z calcd. for
C15H10OF2 + H+ [M + H]+ 245.0778; found 245.0784.
126.7 (ArCH), 46.7 (CH), 40.4 (CH2) ppm. IR (CHCl3): νmax = 3064,
˜
1711, 1494, 1450, 1420, 928, 702 cm–1. HRMS (ESI): m/z calcd. for
Compound 9g: Yield 0.1 g (88 %, over two steps); viscous yellow
liquid; Rf = 0.32 (EtOAc/hexanes, 0.5:0.95); mixture of geometrical
C15H14O2 + Na+ [M + Na]+ 249.0891; found 249.0898.
1
isomer (ca. 1.2:1). H NMR (400 MHz, CDCl3): δ = 9.46 (d, J = 8.0 Hz,
General Procedure for the Synthesis of 3-Aryl Indanones
minor CHO), 9.42 (d, J = 8.0 Hz, major 1 H, CHO), 7.40–7.31 (m, 4 H,
ArH), 7.29–7.28 (m, 3 H, ArH), 7.23–7.21 (m, 2 H, ArH), 7.18–7.16 (m,
4 H, ArH), 7.12–7.09 (m, 4 H, ArH), 6.51 (d, J = 8.0 Hz, 1 H, major =
CH), 6.48 (d, J = 8.0 Hz, minor =CH), 2.35 (s, minor ArCH3), 2.30 (s,
major 3 H, ArCH3) ppm. 13C NMR (100 MHz, CDCl3): δ = 193.7 (CHO),
162.6 (C), 162.4 (C), 141.2 (C), 140.1 (C), 139.8 (C), 136.9 (C), 133.9
(C), 130.9 (CH), 130.8 (CH), 130.5 (CH), 129.5 (CH), 129.1 (CH), 128.9
(CH), 128.7 (CH), 128.6 (CH), 128.4 (CH), 127.2 (CH), 126.6 (CH), 21.5
Procedure (A): Cyclisation with Polyphosphoric Acid (PPA): Com-
pound 7a (0.17 g) was heated with PPA to 90 °C and, after 18–
20 h, the progress of the reaction was monitored by TLC. Upon
completion, the reaction was quenched with ice cold satd. aq. NaH-
CO3 and the aqueous layer was extracted with EtOAc (4 × 5 mL).
The combined organic layers were dried with anhydrous Na2SO4,
concentrated and purified over silica-gel column chromatography
to afford 10a, yield 0.132 g (82 %); colourless solid;[19] m.p. 64–
68 °C; Rf = 0.68 (EtOAc/hexanes, 2:8). 1H NMR (400 MHz, CDCl3): δ =
7.81 (d, J = 7.6 Hz, 1 H, ArH), 7.58–7.54 (m, 1 H, ArH), 7.42–7.39 (m,
1 H, ArH), 7.32–7.21 (m, 4 H, ArH), 7.13–7.11 (m, 2 H, ArH), 4.57 (dd,
J = 8.0, 4.0 Hz, 1 H, CHCH2), 3.22 (dd, J = 19.2, 8.4 Hz, 1 H, CHaHbCO),
2.68 (dd, J = 19.2, 3.6 Hz, 1 H, CHaHbCO) ppm. 13C NMR (100 MHz,
CDCl3): δ = 206.0 (CO), 158.0 (ArC), 143.7 (ArC), 136.8 (ArC), 129.0
(ArCH3) ppm. IR (CHCl3): νmax = 3046, 3005, 1659, 1590, 1575, 1509,
˜
1452, 1445, 1388, 1342, 1248, 1240 cm–1. HRMS (ESI): m/z calcd. for
C16H14O + H+ [M + H]+ 223.1123; found 223.1128.
Compound 9j: Yield 0.264 g (42 %, over two steps); yellow solid;
1
m.p. 124–126 °C; Rf = 0.58 (EtOAc/hexanes, 1:1). H NMR (400 MHz,
CDCl3): δ = 9.55 (d, J = 7.8 Hz, 1 H, CHO), 6.61 (s, 2 H, ArH), 6.53 (s,
Eur. J. Org. Chem. 2016, 2637–2646
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© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim