Basic Ethanol Solution Research Articles

Synthesis of heterocyclic Compounds, XXXVII. Preparation of 4,6‐Diaryl‐1,2‐dihydro‐2‐thioxo‐3,5‐pyridinedicarbonitriles and Related Compounds

AbstractThe reaction of cyanothioacetamide (1) with α‐benzoylcinnamonitriles 2 in basic ethanolic solution leads to 4,6‐diaryl‐1,2‐dihydro‐2‐thioxo‐3,5‐pyridinedicarbonitriles 3 together with the disulfides 4. Treatment of 4 with 2‐mercaptoethanol causes transformation into 3 which can lead to 4 upon reaction with either iodine‐potassium iodide or dimethyl sulfoxide‐trifluoroacetic acid. Methylation of 3 or 4 yields the expected methylthiopyridines 5. On the other hand, reaction of 3 with methyl chloroacetate allows the preparation of thieno[2,3‐b]pyridines 8.

Studies on the autoxidation of carbohydrates and derivatives of carbohydrates in a basic medium. II. A new route for the formation of arabonamide from D-glucose. (2)

When an ethanol solution, in which were dissolved N-aryl-glucosylamine (I) (1 mole) and arylamine (1-1.5 mole) was allowed to stand at room temperature, N, N'-diarylform-amidine salt of D-arabonic acid (III) was initially precipitated (after 1-2 weeks). Secondly 1-aryl-benzimidazol (VI) (VIa, 4' : CH3, 6 : CH3 VIb, 4' : OCH3, 6 : OCH3) and N, N'-diaryloxalamide (VII) were precipitated after a lapse of 30 to 60 days. Finally N, N'-diarylurea (VIII) and azobenzene derivative (IX) were deposited after 40 to 80 days' keep standing. Deposits were all seperated from the residual solution, ethanol being evaporated. The remaining non-volatile residue was extracted with boiling water, and N-aryl-D-arabonamide (IV) was obtained as a water soluble fraction. Similarly, by allowing to stand at room temperature, III, IV, VI and VII were also obtained from the ethanol solution of arylamine and 1-deoxy-1-arylamino-D-fructose (II), Amadori rearranged compound, derived from I. Carbon chain of glucose is decomposed fragmentally at the bond C1-C2 to give arabonic acid formed from the bond C2-C6. By the reaction of arylamine with the fragment C1 separated from the bond C1-C6 of glucose, V, VI, VII and VIII are formed by autoxidation free radically. In the basic ethanol solution of arylamine, the reaction of II with arylamine may possibly proceed in the reverse course to Amadori rearrangement, and the hydrogen at C3 of enaminol (Chart 3), which appears in both courses, is pulled out to form free radical X1. By the intramolecular rearrangement, X is formed from X1. Thus the peroxide begins to initiate the decomposition between C1-C2 of X.