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Helvetica Chimica Acta – Vol. 89 (2006)
Experimental Part
General. Materials obtained from the commercial suppliers were used without further purification.
Anh. Na2SO4 was used as a drying agent. The purity of the compounds was established by TLC and ele-
mental analyses. TLC: plates (E. Merck, Darmstadt, Germany) were prepared according to Stahl (acti-
vated at 1108 for 30 min); AcOEt as solvent; visualization by I2 vapors. Column chromatography (CC):
neutral alumina (E. Merck, Darmstadt, Germany). M.p.: MP1-Veego instrument (Veego Instruments,
Mumbai, India); uncorrected. IR Spectra: Perkin-Elmer-882 spectrophotometer (Perkin Elmer Ltd.,
~
Beaconsfield, England); KBr pellets; nmax in cmÀ1 1H- and 13C-NMR Spectra: Bruker-AC-300F (300
.
MHz) instrument (Bruker AG, Fällanden, Switzerland); Me4Si as internal standard; chemical shifts d
in ppm, J in Hz. MS: Vg-11-250J-70-S spectrometer (VG Analytical Ltd., Manchester, England); in
m/z (rel. %). Elemental analyses (C, H, N): Perkin-Elmer-2400 apparatus.
Monomers 1a–c: The aldehyde (1.81 mmol) was added to a stirred soln. of indan-1-one (0.2 g, 1.51
mmol) in MeOH (25 ml). KOH (0.13 g, 2.27 mmol) was then added, and the mixture was further stirred
or refluxed for a required period of time as specified in the Table (TLC monitoring). Excess MeOH was
evaporated, crushed ice was added, and the mixture was allowed to stand overnight. The precipitate
obtained was filtered, washed thoroughly with dist. H2O, dried, and crystallized from MeOH; 1a–c.
4-[(2,3-Dihydro-1-oxo-1H-inden-2-ylidene)methyl]benzonitrile (1a): Yield 0.182 g (49.05%). M.p.
1
208–2128. IR (KBr): 2980, 2210, 1705, 1630, 1610, 1250, 1100, 740. H-NMR (300 MHz, CDCl3)1): 4.07
(d, J(3,10)=1.0, 2 HÀC(3)); 7.46 (t, Jo =7.4, HÀC(6)); 7.58 (d, Jo =7.7, HÀC(5)); 7.61–7.63 (m, HÀ
C(7), HÀC(10)); 7.75 (s, 4 arom. H (benzonitrile)); 7.93 (d, Jo =7.6, HÀC(8)). Anal. calc. for
C17H11NO (245.28): C 83.25, H 4.52, N 5.71; found: C 83.56, H 4.79, N 5.53.
2,3-Dihydro-2-(3,4,5-trimethoxybenzylidene)-1H-inden-1-one (1b): Yield 59.6%. M.p. 160–1648. IR
(KBr): 3010, 2920, 1690, 1620, 1580, 1500, 1130, 1000, 730. 1H-NMR (300 MHz, CDCl3)1): 3.92 (s, MeOÀ
C(14)); 3.94 (s, MeOÀC(13), MeOÀC(15)); 4.03 (d, J(3,10)=1.3, 2 HÀC(3)); 6.91 (s, HÀC(12), HÀ
C(16)); 7.45 (t, Jo =7.4, HÀC(6)); 7.55–7.63 (m, HÀC(5), HÀC(7), HÀC(10)); 7.91 (d, Jo =7.7, HÀ
C(8)). 13C-NMR (75 MHz, CDCl3)1): 194.06 (C(1)); 153.27 (C(9)); 149.31 (C(13), C(15)); 139.73
(C(2)); 137.9 (C(4)); 134.5 (C(10)); 134.0 (C(6)); 133.66 (C (11)); 130.76 (C(14)); 127.62 (C(7));
126.08 (C(5)); 124.24 (C(8)); 108.08 (C(12), C(16)); 60.91 (MeOÀC(14)); 56.15 (MeOÀC(13), MeOÀ
C(15)); 32.10 (C(3)). Anal. calc. for C19H18O4 (310.35): C 73.53, H 5.85; found: C 73.86, H 5.61.
2,3-Dihydro-2-(4-nitrobenzylidene)-1H-inden-1-one (1c): Yield 60.1%. M.p.>2408. IR (KBr): 3080,
2930, 1690, 1620, 1590, 1335, 1260, 1090, 740. 1H-NMR (300 MHz, CDCl3)1): 4.10 (d, J(3,10)=1.7, 2 HÀ
C(3)); 7.47 (t, Jo =7.3, HÀC(6)); 7.59 (d, Jo =7.2, HÀC(5)); 7.64–7.69 (m, HÀC(7), HÀC(10)); 7.82 (d,
HÀC(13), HÀC(15)); 7.94 (d, Jo =7.7, HÀC(8)); 8.32 (m, HÀC(12), HÀC(16)). Anal. calc. for C16H11NO3
(265.15): C 72.5, H 4.15, N 5.28; found: C 72.39, H 3.99, N 5.49.
Dimers 2a–c. To a stirred soln. of indan-1-one (0.2 g, 1.51 mmol) in MeOH (25 ml), the aldehyde
(1.81 mmol) and KOH (0.13 g, 2.27 mmol) were added. The mixture was further refluxed for a required
period of time as specified in the Table (TLC monitoring). Excess MeOH was evaporated, dist. H2O
added, and the suspension allowed to stand overnight. The obtained precipitate was filtered, washed thor-
oughly with dist. H2O, and air-dried. The crude product was subjected to CC (neutral alumina (25 g),
CH2Cl2): crystalline 2a–c.
4,4’-{1’,3,3’,3a,8,8a-Hexahydro-1’,8-dioxospiro[cyclopent[a]indene-2(1H),2’-[2H]-indene]-1,3-diyl}-
bis[benzonitrile] (2a): Yield 0.28 g (37.7%). M.p. 158–1628. IR (KBr): 3040, 2925, 2245, 1715, 1610, 1480,
1
1305, 1110, 1035, 780. H-NMR (300 MHz, CDCl3)1): 2.92 (d, JAB =17.3, HAÀC(3’)); 3.03 (d, JAB =17.3,
HBÀC(3’)); 3.88 (d, J=10.5, HÀC(10’)); 3.94 (dd, J=8.4, 2.1, HÀC(3)); 4.11 (d, J=10.7, HÀC(10));
4.58 (t, J=9.6, HÀC(2)); 7.00 (t, 2 H, HÀC(16,16’)); 7.32–7.52 (m, 12 arom. H); 7.78 (d, Jo =7.0, 2 H,
HÀC(8,8’)). 13C-NMR (75 MHz, CDCl3)1): 206.24 (C(1) or C(1’)); 204.57 (C(1) or C(1’)); 154.69 (C(9)
or C(9’)); 151.84 (C(9) or C(9’)); 141.92 (C(4) or C(4’)); 141.69 (C(4) or C(4’)); 136.57 (C(6) or
C(6’)); 135.69 (C(6) or C(6’)); 134.96 (C(11,11’)); 132.22 (C(13,13’), C(15,15’)); 129.19 (C(12,12’),
C(16,16’)); 125.89 (C(7,7’)); 124.17 (C(5,5’)); 123.67 (C(8,8’)); 118.36 (2 CN); 111.40 (C(14,14’)); 69.85
(C(2’)); 59.02 (C(2)); 58.85 (C(10)); 53.87 (C(10’)); 45.7 (C(3)); 29.3 (C(3’)). EI-MS: 490 (41, M+),
245 (100, [C17H11NO]+). Anal. calc. for C34H22N2O2 (490.56): C 83.25, H 4.52, N, 5.71; found: C 82.94,
H 4.25, N 6.04.