Chemistry of thienopyridines. XXXV. Synthesis,tautomerism, and reactions of quinoline and thienopyridine systems which bear a 1-carboethoxy-1-cyanomethyl substituent in the pyridine ring,part 2

A comparison is made amongst the isosteric Systems quinoline, thieno[2,3,-b]pyridine, and thieno[3,2-b]-pyridine which bear the 1-carboethoxy-1-cyanomethyl substituent (R) alpha or gamma to the heterocyclic nitrogen atom. Treatment of thieno[3,2-b]pyridine 4-oxide with ethyl cyanoacetate and acetic anhydride at room temperature (Hamana reaction) gives the alpha R-derivative 6 (27%), formulated as an intramolecular H-bonded structure. Neither 6 nor its quinoline alpha analog reacts with refluxing acetic anhydride, while the quinoline gamma isomer 8 , existing as NH and CH tautomers, yields an N-acetyl derivative 10 (70%) under similar conditions. For each of 6 and 8 one can isolate two crystalline forms which differ considerably in color. Compound 10 and its gamma analog in the thieno[2,3-6]pyridine series (previously obtained directly from a Hamana reaction) serve as acetylating agents for aniline, 1-aminobutane, morpholine, and cholesterol. Correlations and contrasts in the three Systems are presented.