PART I. SYNTHESES IN THE QUINOXALINE SERIES:
Several α-hydroxy nitrogen heterocyclic bases have been
treated with an equimolecular mixture of phosphorus oxychloride
and water.
Simple α-hydroxyquinoxalines, acridone, and phenanthridone
are converted to the corresponding chloro derivatives by this
mixture. The mixture is a less efficient chlorinating agent
than phosphorus oxychloride itself.
Derivatives of methin-(2'-(3'-keto) tetrahydroquinoxaline) I
are converted to the corresponding methin-(2'-dihydroquinoxaline)
bases II in good yield by this mixture.
Methin-(2- pyrazinyl)-(2'-dihydroquinoxaline) (II - R =
2-pyrazinyl) and a yellow base, C₁₃H₈N₄, for which the structure
10H- pyrazino (2',3':3,4)cyclopenta(b) quinoxaline III has been
suggested, are obtained when methin-(2-quinoxalinyl)-(2' -(3' -keto)
piperazine) IV is treated with the mixture.
Two bases are also obtained when methin-(2-pyrazinyl)-
(2' -(3'-keto)piperazine) is treated with the mixture. Structures
have been proposed for these bases.
Attempts to synthesise 1'-ketocyclopenta (4',5':2,3) quinoxaline,
the starting material for a proposed synthesis of 10H-pyrazino
(2', 3':3,4)cyclopenta(b)quinoxaline III, have been made.
PART II STUDIES ON CERTAIN QUINOXALINE DERIVATIVES.
This research has been directed toward the elucidation of the
structure of a red base, C₂₀₁H₄N₄, obtained from the reaction of
2-acetyl-3-methylquinoxaline with 2-methylquinoxaline in dilute
acid. A structure, quinoxalo(2',3':8,9)benzo(2,3)-7-methyl-tropazine
V, had been proposed for this base.
An attempt to prepare quinoxalo (2',3':8,9)benzo(2,3)tropazine
by the cyclisation of α-(3-methylquinoxaliny1-2)-ß-(quinoxalinyl-
2')-ethylene was unsuccessful.
Attempts to brominate the C-methyl group with bromine directly
and with N-bromosuccinimide failed.
Attempted oxidations of the C-methyl group with selenium
dioxide, and of the base with hydrogen peroxide, ozone and osmium
tetroxide failed to give identifiable products. Chromic acid
oxidation, however, gave a ketone, C₁₁H₈ or ₉N₂0, for which a
structure has been tentatively advanced.
Investigations into the method of formation of the base have
ruled out the previously proposed method of formation.
Doubt has been cast on the proposed structure of the base
and preliminary investigations of a similar bromo-substituted
red base have been made
