TY - JOUR
T1 - Condensation reactions of dialkoxy-2-phenylchroman-4-ones with 1,2-diamines
T2 - A method for the preparation of chromenoquinoxalines
AU - Watkins, Hannah
AU - Lee, Gerald
AU - Ouedraogo, Pangbewindin H.B.
AU - Padgett, Clifford W.
AU - Nguyen, Khoa
AU - Artis, Rylan
AU - Quillian, Brandon P.
N1 - Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/11/30
Y1 - 2023/11/30
N2 - Reactions of dialkoxy-2-phenylchroman-4-ones (2,3-diethoxy-3-hydroxy-2-phenylchroman-4-one (1) and 2,3-dimethoxy-3-hydroxy-2-phenylchroman-4-one (2)) with various phenylenediamines in refluxing chloroform led to quinoxaline ring formation to produce racemic mixtures of chromenoquinoxaline molecules in good to moderate yields (3–10). The proposed mechanism involves the hemiacetals (1 and 2) rearranging upon heating to form a reactive dione intermediate that subsequently reacts with phenylenediamine derivatives to produce the title compounds. Reactions of 1 and 2 with asymmetric phenylenediamines led to mixtures of two regioisomers, for which the major products were dictated by the relative reactivity of the nucleophilic amine and the electrophilic carbonyl groups. The chromenoquinoxaline products were characterized by 1H, 13C, 19F (when necessary), nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, melting point determination, and in some cases (compounds 6–10) single crystal X-ray diffraction studies. Herein, the synthesis, characterization, and reactivity of this new class of molecules are discussed.
AB - Reactions of dialkoxy-2-phenylchroman-4-ones (2,3-diethoxy-3-hydroxy-2-phenylchroman-4-one (1) and 2,3-dimethoxy-3-hydroxy-2-phenylchroman-4-one (2)) with various phenylenediamines in refluxing chloroform led to quinoxaline ring formation to produce racemic mixtures of chromenoquinoxaline molecules in good to moderate yields (3–10). The proposed mechanism involves the hemiacetals (1 and 2) rearranging upon heating to form a reactive dione intermediate that subsequently reacts with phenylenediamine derivatives to produce the title compounds. Reactions of 1 and 2 with asymmetric phenylenediamines led to mixtures of two regioisomers, for which the major products were dictated by the relative reactivity of the nucleophilic amine and the electrophilic carbonyl groups. The chromenoquinoxaline products were characterized by 1H, 13C, 19F (when necessary), nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, melting point determination, and in some cases (compounds 6–10) single crystal X-ray diffraction studies. Herein, the synthesis, characterization, and reactivity of this new class of molecules are discussed.
KW - Chromane
KW - Chromenoquinoxaline
KW - Condensation
KW - Diamine
KW - Dicarbonyl
KW - Dione intermediate
KW - Hemiacetal
KW - Quinoxaline
UR - http://www.scopus.com/inward/record.url?scp=85176227161&partnerID=8YFLogxK
U2 - 10.1016/j.tetlet.2023.154820
DO - 10.1016/j.tetlet.2023.154820
M3 - Article
AN - SCOPUS:85176227161
SN - 0040-4039
VL - 132
JO - Tetrahedron Letters
JF - Tetrahedron Letters
M1 - 154820
ER -