Thieno[2,3-d]Pyrimidine-4-Ones. Part 5.# Hydrogen Chloride Promoted Synthesis of 2-Substituted Thieno[2,3-d]Pyrimidine-4-Ones and their Structural Investigations
D. Kh. Akramov
Organic Synthesis Department, Institute of the Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent 100170, Uzbekistan
B. B. Zhurayev
National University of Uzbekistan, Chemical Faculty, Tashkent 100195, Uzbekistan
B. A. Urakov
Organic Synthesis Department, Institute of the Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent 100170, Uzbekistan
B. Zh. Elmuradov *
Organic Synthesis Department, Institute of the Chemistry of Plant Substances, Uzbek Academy of Sciences, Tashkent 100170, Uzbekistan
*Author to whom correspondence should be addressed.
Abstract
Synthesis of some novel 2-substituted thieno[2,3-d]pyrimidine-4-ones have been studied. It was found that in this case the 2-amino-4,5-dimethylthiophene carboxamide (1) can serve effective synthone for the synthesis 2-aryl-5,6-dimethyl-3,4-dihydrothieno[2,3-d]pyrimidine-4-ones (3-13). Interaction of amide 1 with substituted aromatic aldehydes in the presence of concentrated hydrochloric acid leads to the formation of compounds 3-13. It was impossible to isolate intermediates (2), substances with asymmetric carbon atom in position 2. It was revealed that intermediates 2 by oxidation on air easily turn into 2-arylthieno[2,3-d]pyrimidine-4-ones. The structure of synthesized compounds was confirmed by IR- and 1H NMR-spectroscopy.
Keywords: Thieno[2,3-d]pyrimidine-4-ones, aromatic aldehydes, electrophilic addition, oxidation, 2-arylthieno[2,3-d]pyrimidine-4-ones