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LETTER
(27) Dendrimer 1b: yield 51%; CHCl3; mp 114–116 °C. 1H
(22) General Procedure for the Preparation of Dendrimer.
A mixture of dienone 6/diketone 7 (1 mmol) and dendritic
bromide 4/9/12 (2.1 mmol) was stirred with K2CO3 (5
mmol) in DMF (20 mL) at 60 °C for 48 h. The reaction
mixture was poured into H2O and extracted with CH2Cl2
(3 × 150 mL). The combined organic extracts were washed
with brine (80 mL), water (2 × 100 mL) and dried over
MgSO4. Evaporation of the organic layer gave a residue,
which was purified by chromatography over SiO2 gel using
CHCl3 as eluent to give the corresponding dendrimer.
(23) Dendrimer 1a: yield 44%; CHCl3; mp 88–92 °C. 1H NMR
(500 MHz, CDCl3): d = 5.14 (s, 4 H), 6.86–6.98 (d, 4 H),
7.17–7.70 (m, 34 H). 13C NMR (125 MHz, CDCl3): d = 70.1,
115.3, 123.6, 125.2, 126.0, 127.7, 127.6, 128.0, 128.8,
130.1, 137.5, 140.7, 142.3, 142.6, 160.7, 188.8. MS (FAB,
70 eV): m/z = 750 [M+]. Anal. Calcd for C55H42O3: C, 88.00;
H, 5.60. Found: C, 87.98; H, 5.56.
NMR (500 MHz, CDCl3): d = 4.90 (s, 4 H), 5.00 (s, 8 H),
6.49 (d, 2 H), 6.57 (d, 2 H), 7.18–7.59 (m, 66 H). 13C NMR
(125 MHz, CDCl3): d = 69.9, 70.2, 101.8, 106.4, 115.3,
125.3, 125.9, 127.3, 127.6, 127.9, 128.8, 130.0, 137.7,
139.1, 140.8, 142.2, 142.6, 143.6, 160.2, 160.5,188.8. MS
(FAB, 70 eV): m/z = 1478 [M+]. Anal. Calcd for C107H82O7:
C, 86.87; H, 5.54. Found: C, 88.76; H, 5.46.
Dendrimer 2b: yield 48%; CHCl3; mp 106–108 °C. 1H
NMR (500 MHz, CDCl3): d = 5.19 (s, 4 H), 5.22 (s, 8 H),
6.73–6.77 (d, 4 H), 7.39–7.79 (m, 70 H). 13C NMR (125
MHz, CDCl3): d = 65.4, 70.1, 70.2, 70.3, 101.4, 101.9,
105.9, 106.5, 114.9, 125.4, 126.0, 127.4, 127.7, 128.9,130.9,
137.8, 140.9, 142.3, 160.3, 160.4, 162.6, 188.4. MS (FAB,
70 eV): m/z = 1582 [M+]. Anal. Calcd for C114H86O8: C,
86.47; H, 5.43. Found: C, 86.40; H, 5.36.
(28) Dendrimer 1c: yield 58%; CHCl3; yellow colored liquid. 1H
NMR (500 MHz, CDCl3): d = 4.98 (s, 4 H), 5.01 (s, 8 H),
5.13 (s, 16 H), 6.70 (d, 2 H), 6.78 (d, 2 H), 7.18–7.81 (m,
130 H). 13C NMR (125 MHz, CDCl3): d = 68.1, 70.1, 101.2,
101.8, 106.6, 115.3, 125.4, 127.4, 127.7, 128.9, 137.9,
139.4, 140.9, 142.3, 160.2, 160.3, 160.6, 188.6. MS
(MALDI-TOF): m/z = 2934 [M+]. Anal. Calcd for
(24) Chudgar, N. K.; Kansara, S. S.; Negai, R.; Sharma, H. C.
Macromol. Rep. 1995, A32, 323.
(25) Dendrimer 2a: yield 45%; CHCl3; mp 174–176 °C. 1H
NMR (500 MHz, CDCl3): d = 5.20 (s, 4 H), 7.04–7.05 (d, 4
H), 7.17–8.00 (m, 38 H). 13C NMR (125 MHz, CDCl3): d =
70.2, 76.7, 114.8, 122.7, 125.2, 126.1, 127.2, 127.6, 128.8,
129.2, 130.9, 131.2, 137.2, 140.7, 142.3, 142.8, 188.4. MS
(FAB, 70 eV): m/z = 854 [M+]. Anal. Calcd for C62H46O4: C,
87.11; H, 5.38. Found: C, 87.05; H, 5.32.
C211H162O15: C, 86.29; H, 5.52. Found: C, 86.20; H, 5.42.
Dendrimer 2c: yield 51%; CHCl3; yellow colored liquid. 1H
NMR (500 MHz, CDCl3): d = 5.00 (s, 4 H), 5.02 (s, 8 H),
5.14 (s, 16 H), 6.67–6.70 (dd, 2 H), 6.75 (d, 2 H), 7.34–7.64
(m, 134 H). 13C NMR (125 MHz, CDCl3): d = 70.1, 70.2,
101.7, 106.5, 114.8, 125.4, 126.0, 127.4, 127.6, 128.9,
137.8, 139.4, 140.9, 142.2, 160.2, 160.3, 188.4. MS
(MALDI-TOF): m/z = 3038 [M+]. Anal. Calcd for
(26) Freeman, A. W.; Christoffels, L. A. J.; Fréchet, J. M. J. J.
Org. Chem. 2000, 65, 7612.
C218H166O16: C, 86.10; H, 5.46. Found: C, 86.06; H, 5.40.
(29) Antibacterial activity: All the test bacteria were subcultured
in nutrient broth from which 1 mL of cell suspension was
taken and was adjusted to 0.5 OD. This was spread as a thin
film over the nutrient agar plates. Concentrations of 60, 40
and 20 mg/mL of the compound were loaded into a disc,
which was placed over the inoculated plates. All the plates
were incubated for 48 h at 37 °C and growth was measured.
A streptomycin disc from Hi-media (10 mg/disc) was used as
the standard.
Synlett 2005, No. 7, 1121–1124 © Thieme Stuttgart · New York