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C. M. M. Santos et al.
LETTER
chromatography (a 7:3 mixture of CH2Cl2–light PE as
eluent). The product was crystallised from EtOH giving, in
each case, the 2,3-diarylxanthones 9a–f (yields described in
Table 2).
(19) Physical Dataof 3-Phenyl-2-(4-methoxyphenyl)xanthone
(8b).
Mp 123–125 °C. 1H NMR (300.13 MHz, CDCl3): d = 3.79
(s, 3 H, 4¢-OCH3), 6.77 (d, 2 H, J = 8.8 Hz, H-3¢,5¢), 7.09 (d,
2 H, J = 8.8 Hz, H-2¢,6¢), 7.20–7.24 (m, 2 H, H-2¢¢,6¢¢), 7.26–
7.30 (m, 3 H, H-3¢¢,4¢¢,5¢¢), 7.39 (dt, 1 H, J = 7.8, 0.9 Hz, H-
7), 7.51 (d, 1 H, J = 8.0 Hz, H-5), 7.53 (s, 1 H, H-4), 7.73 (dt,
1 H, J = 8.0, 1.6 Hz, H-6), 8.34 (s, 1 H, H-1), 8.37 (dd, 1 H,
J = 7.8, 1.6 Hz, H-8). 13C NMR (75.47 MHz, CDCl3): d =
55.2 (4¢-OCH3), 113.4 (C-3¢,5¢), 118.0 (C-5), 119.5 (C-4),
120.7 (C-9a), 121.9 (C-8a), 123.9 (C-7), 126.7 (C-8), 127.5
(C-4¢¢), 128.1 (C-1), 128.2 (C-3¢¢,5¢¢), 129.6 (C-2¢¢,6¢¢), 131.0
(C-2¢,6¢), 132.1 (C-1¢), 134.7 (C-6), 136.7 (C-2), 140.0 (C-
1¢¢), 147.5 (C-3), 155.0 (C-4a), 156.3 (C-4b), 158.6 (C-4¢),
177.0 (C-9). MS (EI): m/z (rel. int.) = 378 (100) [M+•], 363
(12), 347 (9), 334 (7), 318 (3), 305 (9), 292 (2), 276 (4), 263
(2), 213 (3), 189 (5), 173 (3), 167 (5), 138 (3), 92 (2), 77 (2).
Anal. Calcd for C26H18O3: C, 82.52; H, 4.79. Found: C,
82.23; H, 4.94.
(15) Physical Data of 2,3-Diphenylxanthone (8a).
Mp 152–153 °C. 1H NMR (300.13 MHz, CDCl3): d = 7.18–
7.29 (m, 10 H, 2,3-C6H5), 7.41 (dt, 1 H, J = 7.5, 1.0 Hz, H-
7), 7.53 (dd, 1 H, J = 8.4, 0.8 Hz, H-5), 7.57 (s, 1 H, H-4),
7.75 (dt, 1 H, J = 7.8, 1.6 Hz, H-6), 8.38 (dd, 1 H, J = 7.9, 1.6
Hz, H-8), 8.38 (s, 1 H, H-1). 13C NMR (75.47 MHz, CDCl3):
d = 118.0 (C-5), 119.5 (C-4), 120.7 (C-9a), 121.9 (C-8a),
124.0 (C-7), 126.8 (C-8), 126.9 (C-4¢), 127.6 (C-4¢¢), 128.0
(C-2¢,6¢), 128.1 (C-3¢¢,5¢¢), 128.4 (C-1), 129.6 (C-2¢¢,6¢¢),
129.9 (C-3¢,5¢), 134.8 (C-6), 137.0 (C-1¢), 139.8 (C-2), 139.9
(C-1¢¢), 147.6 (C-3), 155.2 (C-4a), 156.3 (C-4b), 177.0 (C-
9). MS (EI): m/z (rel. int.) = 348 (100) [M+•], 347 (45), 333
(14), 318 (8), 305 (4), 289 (15), 276 (4), 228 (8), 226 (8), 213
(5), 174 (9), 145 (4), 77 (3). HRMS (EI): m/z calcd for
C25H16O2: 348.1150; found: 348.1158.
(16) Physical Data of 2,3-Diphenyl-3,4-dihydroxanthone
(10a).
(20) Physical Data of 3-(4-Benzyloxyphenyl)-2-(3,4-di-
methoxyphenyl)-3,4-dihydroxanthone (10f).
1H NMR (300.13 MHz, CDCl3): d = 3.01 (dd, 1 H, J = 17.4,
1.5 Hz, H-4trans), 3.67 (dd, 1 H, J = 17.4, 9.0 Hz, H-4cis), 4.31
(dd, 1 H, J = 9.0, 1.5 Hz, H-3), 7.19–7.30 (m, 8 H, H-
2¢,3¢,4¢,5¢,6¢,3¢¢,4¢¢,5¢¢), 7.32–7.41 (m, 2 H, H-5,7), 7.46–7.50
(m, 2 H, H-2¢¢,6¢¢), 7.56 (s, 1 H, H-1), 7.60 (dt, 1 H, J = 7.8,
1.6 Hz, H-6), 8.29 (dd, 1 H, J = 7.9, 1.6 Hz, H-8). 13C NMR
(75.47 MHz, CDCl3): d = 36.7 (C-4), 41.7 (C-3), 116.8 (C-
1), 116.9 (C-9a), 118.0 (C-5), 123.9 (C-8a), 125.1 (C-7),
125.7 (C-2¢¢,6¢¢), 126.2 (C-8), 127.2 (C-4¢), 127.4 (C-2¢,6¢),
127.6 (C-4¢¢), 128.5 (C-3¢¢,5¢¢), 129.0 (C-3¢,5¢), 133.0 (C-6),
135.3 (C-1¢¢), 139.1 (C-1¢), 140.7 (C-2), 155.9 (C-4b), 162.5
(C-4a), 174.2 (C-9). MS (FAB+): m/z (rel. int.) = 351 (37) [M
+ H]+, 212 (8), 77 (19). HRMS (EI): m/z calcd for C25H18O2:
350.1307; found: 350.1315.
1H NMR (300.13 MHz, CDCl3): d = 2.95 (dd, 1 H, J = 17.3,
1.5 Hz, H-4trans), 3.61 (dd, 1 H, J = 17.3, 8.4 Hz, H-4cis), 3.83
and 3.84 (2 s, 6 H, 3¢,4¢-OCH3), 4.23 (d, 1 H, J = 8.3 Hz, H-
3), 4.94 (s, 2 H, 4¢¢-OCH2C6H5), 6.74 (d, 1 H, J = 8.5 Hz, H-
5¢), 6.84 (d, 2 H, J = 8.7 Hz, H-3¢¢,5¢¢), 6.97 (dd, 1 H, J = 8.5,
2.1 Hz, H-6¢), 7.09 (d, 1 H, J = 2.1 Hz, H-2¢), 7.21 (d, 2 H,
J = 8.7 Hz, H-2¢¢,6¢¢), 7.28–7.39 (m, 7 H, H-5,7 and H-
2,3,4,5,6 of 4¢¢-OCH2C6H5), 7.44 (s, 1 H, H-1), 7.57 (dt, 1 H,
J = 7.8, 1.6 Hz, H-6), 8.28 (dd, 1 H, J = 7.9, 1.6 Hz, H-8). 13
C
NMR (75.47 MHz, CDCl3): d = 36.7 (C-4), 41.1 (C-3), 55.8
(3¢,4¢-OCH3), 69.9 (4¢¢-OCH2C6H5), 108.7 (C-2¢), 110.8 (C-
5¢), 114.8 (C-1), 115.2 (C-3¢¢,5¢¢), 116.9 (C-9a), 118.0 (C-5),
118.3 (C-6¢), 123.8 (C-8a), 125.0 (C-7), 126.1 (C-8), 125.7
(C-2,6 of 4¢¢-OCH2C6H5), 127.9 (C-4 of 4¢¢- OCH2C6H5),
128.3 (C-2¢¢,6¢¢), 128.5 (C-3,5 of 4¢¢-OCH2C6H5), 132.0 (C-
1¢), 133.0 (C-6), 133.1 (C-1¢¢), 135.5 (C-2), 136.9 (C-1 of 4¢¢-
OCH2C6H5), 148.7 and 148.8 (C-3¢,4¢), 155.8 (C-4b), 157.9
(C-4¢¢), 162.3 (C-4a), 174.2 (C-9). HRMS (EI): m/z calcd for
C32H24O3: 456.1725; found: 456.1735.
(17) (a) Clarke, D. S.; Gabbutt, C. D.; Hepworth, J. D.; Heron, B.
M. Tetrahedron Lett. 2005, 46, 5515. (b) de Meijere, A.;
Schelper, M.; Knoke, M.; Yucel, B.; Sünnemann, H. W.;
Scheurich, R. P.; Arve, L. J. Organomet. Chem. 2003, 687,
249.
(18) Santos, C. M. M.; Silva, A. M. S.; Cavaleiro, J. A. S.
unpublished results.
(21) The relative stereochemistry of protons H-3 and H-4 is
referred as cis and trans.
Synlett 2005, No. 20, 3095–3098 © Thieme Stuttgart · New York