| Abstract: | Deuteriodeprotonation of some substituted 4,5-borazarothieno2,3-c]pyridines (I) and 7,6-borazarothieno3,2-c]pyridines (II) has been studied by the nmr technique. Exchange occurred predominantly in the 3-position, and the effect of methyl substitution on rate is discussed. The rates of exchange in some derivatives of I and II were compared with those of the isoelectronic thieno2,3-c]pyridines (III) and thieno3,2-c]pyridines (IV). Similar rates were obtained, confirming the aromatic nature of I and II. The deuteriodeprotonation of 4-methyl-4,5-borazaro-thieno2,3-c]pyridine (Ie), 7-methyl-7,6-borazarothieno3,2-c]pyridine (IIe), 4-methylthieno-2,3-c]pyridine (IIIe), and 7-methylthieno3,2-c]pyridine (IVe) were measured at different concentrations of deuteriosulfuric acid and different temperatures, showing that the protonated heterocycles are substrates in the deuteriodeprotonation reaction. Standard rates at p0 H and 100° were calculated for these systems. |
