Experimental

Infrared spectra were recorded on a Perkin-Elmer 1600 FT-IR spectrophotometer and NMR spectra were recorded in deuterochloroform (except where otherwise stated) on a Joel PMX 60si spectrometer using tetramethylsilane as internal reference. Melting points were determined with an Electrothermal melting point apparatus and were uncorrected. Reactions were monitored by thin layer chromatography on Merck DC-Alufolien Kieselgel 60 F₂₅₄ (Merck # 5554) plates which were visualised under ultraviolet irradiation.

Example procedure

Reaction of 3-Cyano-2(1H)-pyridinethione 3 with chloroacetonitrile :

3-Cyano-2(1H)-pyridinethione 3 (1.0g, 7.48 mmol) was added to an ice cold mixture of DMF (20ml) and sodium ethoxide (890mg, 16.46mmol). The reaction mixture was stirred for 5 minutes at ice temperature and chloroacetonitrile (621mg, 8.23mmol) added dropwise. The reaction mixture was stirred for a further 10 minutes at ice temperature, for 2 hours at room temperature, poured onto ice (150g) and the crude product obtained by filtration. The solid was dissolved in ethyl acetate, dried over magnesium sulfate, decolourised with charcoal and the solvent removed in vacuo. Recrystallisation from ethyl acetate afforded 3-amino-2-cyanothieno[2,3-b]pyridine 5 (965mg, 72%) as a yellow crystalline solid mpt 218-220^oC (lit⁸ 218-220^oC).

(See Tables 1 & 2)