Reaction of 3,5-bis(trimethylsilyl)-4-chloropyridine [
1] with thiophenol gave 3,5-bis(trimethylsilyl)-4- thiophenoxypyridine, a potential precursor to novel pyridinylidene derived nonlinear optical materials.
To an ice-cooled, stirred solution of 3,5-bis(trimethylsilyl)-4-chloropyridine (2.57 g, 10 mmol) in triethylamine (2 mL) was added portion-wise over 5 min neat thiophenol (1.38 g, 1.29 mL, 12.5 mmol). The mixture became quite viscous and a further 2-3 mL of triethylamine was added to ensure efficient mixing of the solution. The mixture was refluxed overnight, cooled, diluted with water (50 mL) and extracted with chloroform (3 x 50 mL). The combined organic extracts were washed with water (50 mL), dried (Na2SO4) and concentrated under vacuum to an orange oil. Flash column chromatography, eluting initially with hexanes to remove unchanged thiophenol and then with ethyl acetate:hexanes (1:4) gave, after concentration of the most mobile fraction under vacuum, a light yellow-orange oil. Prolonged pumping under vacuum gave a pale yellow solid (2.35 g) which was recrystallised (hexanes) to give the desired product as colourless prisms (1.61 g, 49 %).
M.p. 67-69 °C.
IR (nujol): 1583, 1520, 1368, 1181, 1066, 1025, 857.
1H NMR (300 MHz, CDCl3): 0.00, s, 18H; 6.46-6.49, m, 2H; 6.79-6.84, m, 1H; 6.90-6.95, m, 2H; 8.55, s, 2H.
13C NMR (75 MHz, CDCl3): d 0.0 (CH3), 124.8 (CH), 125.3 (CH), 128.7 (CH), 139.6 (CQ), 142.3 (CQ),
153.6 (CQ), 156.6 (CH).
HRMS (FAB): Found: MH+ m/z 332.13296 C17H25NSSi2 requires 332.13191 D = 3.2 p.p.m.
Anal. Calc for C17H25NSSi2 C 61.57, H 7.60, N 4.22. Found C 61.31, H 7.42, N 4.27.