In the first part of my masters thesis I synthesized a series of 2H-pyran-2-ones and performed a hydrolysis of 3-benzyolamino moiety thus isolating a 3-amino 2H-pyran-2-one, from which I synthesized a hydrochloride salt, a secondary amine with trityl chloride, two 2H-pyran-2-ones with substituted benzoylamino groups and a series of symmetric bis(2-oxa-2H-pyran-3-yl)diamides. Various alcohols were transformed into a set of dialkyl acetylenedicarboxylates that were employed for Diels–Alder reactions with 2H-pyran-2-ones to form aromatic dialkyl phthalates. In two of these cases an oxazine side product was detected (and its structure proven by X-ray diffraction analysis) and in one case an additional Diels–Alder reaction took place on the furan ring, followed by acetylene elimination. Phthalate synthesis conditions were optimized in accordance with green chemistry aspects, replacing high-boiling point solvents with xylene as a more acceptable alternative and carried out under thermal conditions in sealed ACE tubes. To investigate the electronic effects of various substituents on pyranone ring and consequently determine the reactivity for Diels–Alder reactions, a series of competitive experiments were carried out, after which 2H-pyran-2-ones were arranged according to their reactivity; the obtained order was in excellent agreement with the results obtained by quantum-mechanical calculations. A similar study of reactivity was preformed for acetylenedicarboxylates in combination with one 2H-pyran-2-one. Prepared phthalates were used for the derivatizations with nitrogen nucleophiles yielding a series of isoindolindiones, one of which displayed isomerization from the kinetically controlled pyrrole form into thermodynamically more stable pyridazine form. I also synthesized a pyridine salt, which is a known dienophile in the literature, however reaction with 2H-pyran-2-one was not successful.
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