237. The chemistry of the pyrrocolines. Part II. Nitroso-derivatives of some substituted pyrrocolines

The Chemistry of the Pyrrocolines and the Octahydropyrrocolines.

“…The action of excess concentrated nitric acid either alone or in acetic acid solution on the monoacetyl derivatives of 2-methyland 2-phenyl-pyrrocolines also gives the 1,3-dinitro compounds, but attempts to effect mononitration under the conditions used by Scholtz for 1,3-diacetylpyrrocoline were unsuccessful. However, with 3-acetyl-2-methylpyrrocoline it is possible to prepare l-nitro-3-acetyl-2-methylpyrrocoline, thus showing that in acetic acid solution the 1-position is substituted before the acetyl group is re- The nitroacetyl derivatives of 2-methyl-and 2-phenyl-pyrrocolines have also been obtained from the corresponding 1 -nitroso-3-acetylpyrrocolines by careful oxidation with perhydrol (13), and 3-nitro-2-methylpyrrocoline has been prepared in small yield from the 3-nitroso compound in the same way (12). By the action of concentrated nitric acid on these nitroso derivatives the 1,3-dinitropyrrocolines are obtained.…”

“…VV Extension of this synthesis is exemplified by the preparation of -isonitrosophenacyl-a-picolinium chloride, from which 3-nitroso-2-phenylpyrrocoline arose in excellent yield (12). In contrast, the preparation of the corresponding quaternary nitro body from -nitrobromoacetophenone could not be effected (13).…”

“…Here, however, the reactive pyrrole ring is protected by the carboxylic ester groups. The successful oxidation of nitroso to nitro groups in the pyrrocoline nucleus has been effected under critical conditions with perhydrol (12,13). This agent, however, rapidly attacks the nucleus and is thus useful for degradative purposes (Section XIII).…”

“…The acyl groups are readily removed from these compounds by hydrolysis with mineral acids (11,19,20,81,83) and even boiling aqueous acetic acid is effective with 3-acetyl-2-phenylpyrrocoline (11). Diacyl derivatives appear to be somewhat more resistant than monoacyl derivatives (11) and those compounds containing a nitro (13,82) or nitroso (12) group in the nucleus cannot be hydrolyzed in this way. 3-Acetylpyrrocoline has been reported to be stable to boiling alcoholic potash (82) but heating 3-acetyl-2-phenylpyrrocoline in alcoholic solution in the presence of sodium ethoxide at high temperature and pressure removed the acetyl group (14).…”

“…By the action of concentrated nitric acid on these nitroso derivatives the 1,3-dinitropyrrocolines are obtained. The direct nitrosation of the pyrrocoline nucleus has been applied to 2-methyland 2-phenyl-pyrrocolines and their 3-acetyl derivatives and to 2-methyl-3ethylpyrrocoline (12,54) to yield the mononitroso compounds.…”