V. Georgakilas et al. / Tetrahedron 58 %2002) 2441±2447
2445
nmax ,KBr) 3081, 3032, 2958, 2870, 1652 ,CvO), 1600,
1281, 1252, 847 ,C±Si) cm21; dH ,400 MHz, CDCl3)
7.28±7.80 ,9H, m, Ar-H), 1.41 ,6H, s, CH3), 20.07 ,9H,
s, SiMe3); dC ,100 MHz, CDCl3) 196.4 ,CvO), 154.9,
138.2, 131.9, 129.9, 129.8, 128.1, 125.9, 125.8 ,Carom),
28.3 ,C±SiMe3), 23.8 ,CH3), 24.2,Si Me3); GC±MS m/z
,%): 296 ,M1, 27), 281 ,M12Me, 20), 105 ,PhCO, 12), 77
,Ph, 18), 73 ,SiMe3, 100).
,100 MHz, CDCl3) 197.7 ,CvO), 155.4, 133.2, 127.8,
126.1 ,Carom), 28.3 ,C±SiMe3), 26.3 ,CH3CO), 23.7 ,CH3),
24.3 ,SiMe3); GC±MS m/z ,%): 234 ,M1, 17), 2 19
,M12Me, 2), 177 ,M12MeCO, 3), 73 ,SiMe3, 100).
3.3. Xanthene derivatives
General procedure %monosubstituted derivatives 4a, b and
e). In a mixture of xanthene ,11 mmol) and AlCl3 ,13 mmol)
in carbon disul®de ,20 ml) or in a mixture of 9-,trimethyl-
silyl)xanthene ,7.86 mmol) and AlCl3 ,8.6 mmol) in carbon
disul®de ,10 ml) was added 13 or 8.6 mmol benzoyl ,or
acetyl) chloride, respectively, during a period of ,15 min.
The mixture was heated at ,408C until the reaction was
completed ,TLC control). The mixture was hydrolyzed
with water/ice mixture ,20 ml) and diluted with dichloro-
methane ,30 ml). The organic layer was neutralized with a
10% solution of NaHCO3 and was dried over NaSO4.
Removal of the solvent under vacuum gave the crude
product, which was puri®ed by recrystallization.
3.2.5.
4-)Trimethylsilylmethyl)acetophenone
)2e).
According to the general procedure 2.38 g ,70%) of 2e
was isolated after fractional distillation ,758C/0.03 Torr).
The product solidi®ed after a while, mp 44±458C ,ethanol),
[lit. 39±40.58C];13 nmax ,KBr) 3028, 2958, 2895, 1676
,CvO), 1602, 1270, 1248, 853 ,C±Si) cm21
; dH
,400 MHz, CDCl3) 7.81±7.83 ,2H, d, J8.2Hz, Ar-H),
7.05±7.07 ,2H, d, J8.1 Hz, Ar-H), 2.56 ,3H, s, CH3),
2.17 ,2H, s, CH2), 20.07 ,9H, s, SiMe3); dC ,62.9 MHz,
CDCl3) 197.7 ,CvO), 147.2, 133.4, 128.4, 127.9 ,Carom),
27.9 ,CH2±SiMe3), 26.3 ,CH3CO), 22.0 ,SiMe3); GC±MS
m/z ,%): 206 ,M1, 35), 191 ,M12Me, 9), 115 ,3), 73
,SiMe3, 100).
Disubstituted derivatives 4c, d and f. For the synthesis of
disubstituted derivatives the molar ratio between the
xanthene substrate, the AlCl3 catalyst and the benzoyl ,or
acetyl) chloride was 1:2:2, respectively.
3.2.6. 4-[Phenyl)trimethylsilyl)methyl]acetophenone )2f).
According to the general method this product was
obtained as white crystals ,3.3 g, 70%), mp 66±678C
,ethanol) after column chromatography ,SiO2, hexane/
ethylacetate 9/1); [Found: C, 76.63; H, 7.89. C18H22OSi
requires C, 76.54; H, 7.85%]; nmax ,KBr) 3050, 3020,
2945, 2885, 2865, 1670 ,CvO), 1598, 1273, 1249, 845
,C±Si), 750, 703 cm21; dH ,250 MHz, CDCl3) 7.82,2H,
d, J8.3 Hz, Ar-H), 7.10±7.31 ,7H, m, Ar-H), 3.59 ,1H,
s, CH), 2.54 ,3H, s, CH3), 0.03 ,9H, s, SiMe3); dC
,62.9 MHz, CDCl3) 197.7 ,CvO), 149.1, 141.8, 134.2,
128.9, 128.5, 125.5 ,Carom), 48.7 ,CH±SiMe3), 26.4
,CH3CO), 21.8 ,SiMe3).
3.3.1. 2-)Benzoyl)xanthene )4a). 2.9 g ,93%) of 4a was
obtained as white crystals according to the general method,
mp 149±1508C, ,ethanol/chloroform 3/2); [Found: C, 84.20;
H, 4.88. C20H14O2 requires C, 83.90; H, 4.93%]; nmax ,KBr)
3040, 2913, 2835, 1642 ,CvO), 1594, 1478, 1449, 1246,
752, 728, 693 cm21; dH ,400 MHz, CDCl3) 7.78 ,2H, d,
J7.5 Hz, Ar-H), 7.71 ,1H, s, xanthene-H1), 7.67 ,1H, dd,
J8.4, 2.1 Hz, xanthene-H3), 7.57 ,1H, tt, J7.4, 1.5 Hz,
Ar-H), 7.47 ,2H, tt, J7.5, 1.5 Hz, Ar-H), 7.01±7.24 ,5H,
m, xanthene-H4±8), 4.09 ,2H, s, xanthene-H9); dC
,62.9 MHz, CDCl3) 195.5 ,CvO), 155.4 ,q), 151.3 ,q),
138.0 ,q), 132.3 ,q), 132.1, 131.7, 130.5, 129.8, 129.0,
128.2, 127.9, 123.7, 120.5 ,q), 119.9 ,q), 116.6, 116.3
[Carom], 27.6 ,CH2); MS ,EI, 70 eV): m/z ,%): 286 ,M1,
100), 209 ,M12C6H5, 38), 181 ,M12COC6H5, 54), 105
,C6H5CO, 14), 77 ,C6H5, 25).
3.2.7. 4-[Methyl)trimethylsilyl)methyl]acetophenone )2g).
2.3 g ,63%) of 2g was prepared according to the general
procedure. The white crystals melt around the room
temperature ,ethanol); [Found: C, 70.88; H, 9.27.
C13H20OSi requires C, 70.85; H, 9.15%]; nmax ,neat) 3031,
3001, 2957, 2900, 2873, 1682 ,CvO), 1603, 1270, 1249,
850 ,C±Si) cm21; dH ,400 MHz, CDCl3) 7.86 ,2H, d,
J8.2Hz, Ar-H), 7.11 ,2H, d, J8.2Hz, Ar-H), 2.56 ,3H,
s, CH3CO), 2.28 ,1H, q, J7.4 Hz, CH), 1.38 ,3H, d,
J7.4 Hz, CH3), 20.05 ,9H, s, SiMe3); dC ,100 MHz,
CDCl3) 197.8 ,CvO), 152.5, 133.7, 128.2, 126.9 ,Carom),
30.7 ,CH±SiMe3), 26.3 ,CH3CO), 14.4 ,CH3), 23.4
,SiMe3); GC±MS m/z ,%): 220 ,M1, 23), 177
,M12MeCO, 3), 73 ,SiMe3, 100); HRMS ,EI): M1,
found 220.1281. C13H20OSi requires 220.1283.
3.3.2. 2,7-)Dibenzoyl)xanthene )4b). According to the
general method 4b was obtained as white crystals 2.7 g
,63%), mp 253±2548C, ,toluene); [Found: C, 82.87; H,
4.52. C27H18O3 requires C, 83.06; H, 4.65%]; nmax ,KBr)
3042, 2910, 2835, 1642 ,CvO), 1615, 1590, 1478, 1437,
1275, 727, 690 cm21; dH ,400 MHz, CDCl3) 7.78 ,4H, dd,
J7.6, 1.4 Hz, Ar-H), 7.73 ,2H, s, xanthene-H1,8), 7.71 ,2H,
dd, J8.4, 2.1 Hz, xanthene-H3,6), 7.59 ,2H, tt, J7.4,
1.3 Hz, Ar-H), 7.49 ,4H, tt, J7.6, 1.3 Hz, Ar-H), 7.15
,2H, d, J8.3 Hz, xanthene-H4,5), 4.16 ,2H, s, xanthene-
H9); dC ,62.9 MHz, CDCl3) 195.4 ,CvO), 154.6, 137.8,
133.1, 132.3, 131.6, 130.7, 129.8, 128.3, 120.0, 116.5
,Carom), 27.5 ,CH2); MS ,EI, 70 eV): m/z ,%): 390 ,M1,
100), 313 ,M2C6H5, 45), 285 ,M12COC6H5, 50), 105
,C6H5CO, 32), 77 ,C6H5, 34).
3.2.8. 4-[Dimethyl)trimethylsilyl)methyl]acetophenone
)2i). 2.33 g ,60%) of 2i was isolated according to the general
procedure, mp 44±468C ,ethanol) after puri®cation with
column chromatography ,silica gel 60, petroleum ether/
ethylacetate 10/1); [Found: C, 71.73; H, 9.50. C14H22OSi
requires C, 71.74; H, 9.47%]; nmax ,KBr) 3061, 3044,
2960, 2869, 1681 ,CvO), 1602, 1273, 1247, 838
3.3.3. 2-Benzoyl-9-)trimethylsilyl)xanthene )4c). 1.58 g
,56%) of 4c was isolated as white crystals mp 112±1138C
,ethanol/chloroform 1/1); [Found: C, 77.13; H, 5.83; Si,
8.41. C23H22O2Si requires C, 77.06; H, 6.19; Si, 7.83%];
,C±Si) cm21
; dH ,400 MHz, CDCl3) 7.87 ,2H, d,
J8.2 Hz, Ar-H), 7.26 ,2H, d, J8.2Hz, Ar-H), 2.56 ,3H,
s, CH3CO), 1.38 ,6H, s, CH3), 20.08 ,9H, s, SiMe3); dC