Supramolecular Chemistry
633
cooling and removal of the ethylene glycol layer with a
separatory funnel, evaporation of the toluene gave white
plates that were recrystallised from toluene. m.p. 153–
1558C 1H NMR (CDCl3) 3.00 (s, 6H), 4.33 (s, 4H) 6.67 (d,
2H, J ¼ 8.8) 7.69 (d, 2H, J ¼ 8.8); 13C NMR (CDCl3)
40.14, 65.89, 111.35, 129.19, 136.32, 152.68; IR (NaCl
plate) 2900 (CZH), 1600 (aromatic CvC); EI-MS
191(M þ , 72), 190 (100), 189 (23).
ethanol (40 ml), and 6 mmol 2-hydrazinopyridine in
ethanol was added. Slow evaporation of the ethanol
precipitated the bishydrazone as an orange solid (220 mg,
98%) with 1H NMR (dmso-d6) 11.53 (s, 2H), 8.25 (d, 2H,
J ¼ 9.1), 8.19 (ddd, 2H, J ¼ 4.9, 1.8, 0.8), 8.05 (s, 2H),
7.99 (s, 1H), 7.76 (ddd, 2H, J ¼ 8.2, 7.2, 1.8), 7.39 (dt, 2H,
J ¼ 8.2, 0.8), 6.89 (ddd, 2H, J ¼ 7.2, 4.9, 0.8), 6.8 (d, 2H,
J ¼ 9.06), 3.31 (s, 6H); 13C NMR (dmso-d6) 164.1, 160.1,
156.2, 152.0, 147.9, 138.4, 137.6, 129.0, 124.2, 116.3,
111.4, 106.9, 105.2. HETCOR indicates that the N-methyl
carbons are near 40 ppm and lost under the solvent peak;
IR (NaCl plate) 3203(CZH), 1606 (aromatic CvC);
HRMS 438.2156 (M þ H, calcd 438.2155) 460.1973
(M þ Na, calcd 460.1974).
2-(40-Dimethylaminophenyl)-4,6-dimethylpyrimidine
(10)
To a solution of 764 mg (4 mmol) of 4-dimethylaminophe-
nylboronic acid ethylene glycol ester and 936 mg (4 mmol)
4,6-dimethyl-2-iodopyrimidine in 20 ml dioxane were
added 0.1 g of PPh3 (0.4 mmol), 0.02 g of Pd(OAc)2
(0.1 mmol) and 8 ml 1 M aqueous NaOH. The reaction
mixture was degassed and heated at 70–808C for 3 h. The
cooled mixture was extracted with 3 £ 100 ml portions of
ethyl acetate. Organic extracts were combined and back
extracted with 3 £ 100 ml portions of 0.5 N HCl. The
aqueous layer was neutralised with 1 N NaOH solution to
pH 6 where the product precipitated as a cream solid and
was isolated by filtration. Recrystallisation from heptane
gave white needles (0.75 g, 80%) with m.p. 158–1608C; 1H
NMR (CDCl3) d 2.48 (s, 6H), 3.03 (s, 6H), 6.75 (d, 2H,
J ¼ 9), 6.78 (s, 1H), 8.33 (d, 2H, J ¼ 9); 13C NMR (CDCl3)
d 24.3, 40.3, 111.7, 116.4, 126.0, 129.4, 152.0, 164.5,
166.4; IR (NaCl plate) 2920 (CZH), 1606 (aromatic
CvC); EI-MS 227 (Mþ, 100), 226 (90), 211 (11), 145 (11).
2-(40-Dimethylaminophenyl)-pyrimidine-4,6-
dicarboxaldehyde bis(2-pyridyl methyl hydrazone) (8)
2-(40-Dimethylaminophenyl)-pyrimidine-4,6-dicarboxal-
dehyde bis(2-pyridyl hydrazone) (18 mg) was combined
with excess NaH in THF and excess MeI and stirred until
the purple colour was entirely dissipated. Dilution with
water, extraction with dichloromethane, evaporation and
recrystallisation gave the dimethyl hydrazone (13 mg,
1
70%) H NMR (dmso-d6) 8.33 (d, 2H J ¼ 8.8 Hz), 8.30
(2H dd, J ¼ 5, 2 Hz), 8.14 (s, 1H), 7.78 (d, 2H, J ¼ 8.5),
7.65 (s, 2H), 7.58 (2H, ddd, J ¼ 2, 7, 8.5), 6.81(2H, dd,
J ¼ 5, 7), 7.72 (d, 2H, J ¼ 8.8), 3.67 (s, 6H), 2.99 (s, 6H);
13C NMR (dmso-d6) 165.1, 161.8, 157.2, 152.1,
147.1,137.5, 133.5, 129.4, 116.7, 111.7, 110.3, 106.3,
40.3, 29.9; IR 1604 (aromatic CvC); HRMS 466.2468
(M þ H, calcd 466.2467).
2-(40-Dimethylaminophenyl)-pyrimidine-4,6-
dicarboxaldehyde (12)
To a solution of 2-(40-dimethylaminophenyl)-4,6-
dimethylpyrimidine (0.68 g, 3 mmol) in dioxane (20 ml)
were added SeO2 (6.2 mmol) and trifluoroacetic acid
(7 ml). The solution was heated under reflux for 2 h, then
filtered and neutralised with saturated NaHCO3 solution.
The mixture was then extracted with dichloromethane, and
the organic extract was filtered through a plug of silica gel.
Evaporation gave an orange solid containing the
dicarboxaldehyde, 131 mg, 0.51 mmol (17%) 1H NMR
(CDCl3) 3.03 (s, 6H), 6.75 (d, 2H, J ¼ 9 Hz), 7.86 (s, 1H),
8.41 (d, 2H J ¼ 9 Hz), 10.05 (s, 2H); 13C NMR (CDCl3)
40.3, 107.9, 111.8, 130.2, 130.3, 152.8, 160.2, 16.1, 192.8;
IR (NaCl plate) 2920, 2846 (CZH), 1719 (CvO), 1606
(aromatic CvC); EI-MS 255 (M þ , 100), 254 (80) 198
(15), 145 (30). This solid was not purified further but used
directly in the next step.
2-(p-Methoxyphenyl)-4,6-dimethylpyrimidine (11)
To a solution of 8 mmol (1.22 g) of p-methoxyphenyl-
boronic acid and 8 mmol (1.87 g) 2-iodo-4,6-dimethylpyr-
imidine in 50 ml dioxane were added 0.1 g of PPh3
(0.4 mmol), 0.02 g of Pd(OAc)2 (0.1 mmol) and 15 ml aq
1 M NaOH solution. The reaction mixture was heated
under nitrogen at 70–808C for 3 h. Then the cooled
mixture was diluted with ethyl acetate and extracted with
0.5 N HCl. The aqueous layer was neutralised with 1 N
NaOH solution whereupon the solution turned cloudy and
upon standing a crystalline precipitate of the product was
isolated by filtration. The crude product was purified by
recrystallisation from heptane to give 0.9 g (4.2 mmol,
53%) of white crystals with m.p. 95–968C 1H NMR
(CDCl3) d 2.509 (s, 6H), 3.88 (s, 3H), 6.97 (s, 1H), 6.861
(d, 2H, J ¼ 9), 8.387 (d, 2H, J ¼ 9); 13C NMR (CDCl3) d
24.2, 55.4, 113.8, 117.3, 129.9, 131.1, 161.6, 163.9, 166.6;
MS m/z 214 (M þ , 100), 199 (30), 171 (10), 133 (15);
IR (NaCl plate) 2997, 2970, 2935, 2835, (CZH), 1591
(CvC).
2-(40-Dimethylaminophenyl)-pyrimidine-4,6-
dicarboxaldehyde bis(2-pyridyl hydrazone) (4H2)
Crude 2-(40-dimethylaminophenyl)-pyrimidine-4,6-dicar-
boxaldehyde (130 mg, 0.5 mmol) was redissolved in