Aza‐, Di‐ und Triazaxanthone aus Azachromonen

Abstract

Eiden und RademacherArch. Phann. The E isomer recrystallized form methano1:m.p. 2W203" (110 mg). 'H-NMR: 6 (ppm): 1.42 (s, 6H), 2.03(~,3H),4.82(d,J =5.4Hz,2H),5.61(s,lH),6.78(t,J=5.4Hz,lH),6.868.37(7H,aromatic protons). C2,H,05 (376.Die aus den pyridylsubstituierten 1,3-Dicarbonyl-Verbindungen 5s und Sb herstellbaren Acylmethylthio-azachromone 7s und 7b setzten sich mit Aminen, Hydrazin und Amidinen bzw. CH-aciden Verbindungen zu den Azaxanthonen 88, Eb, 9s und 9b, 11s und l l b bzw. U und 14 um. 0365-6233/85/1010-092 S U2.50/0 0 VCH Vcrlagsgesellschaft mbH. D-6940 Weinhcim, 1985

2-(Substituted amino)-8-azachromones from 4,6-Diaryl-2-pyridones: A Synthetic Strategy toward Compounds of Broad Structural Diversity

“…The reported procedure uses potassium hydroxide (2 equiv) as base to promote the condensation with CS 2 (3 equiv) in DMSO, followed by treatment with dimethyl sulfate (4 equiv). , Under these conditions, diketone 3a gave rise to a mixture of the 2-(methylthio)-8-azachromone 4a (34%) and of the 2-methyl derivative 5a (35%) as an intramolecular O-arylation byproduct (Scheme ). As discussed in the Introduction, the O-arylation ring closure of 2-pyridones has been mainly reported through dehydration under acidic conditions, and 5a is indeed the main product observed (89%) after a 1 h treatment of 3a in sulfuric acid (Scheme ).…”

“…The intramolecular O-arylation has been the most explored and can be performed under acid catalysis for 2-pyridones , and 2-methoxypyridines, under base catalysis for 2-halopyridines, and via CH activation of N -oxides for 2-unsubstituted pyridine derivatives (Scheme A). By contrast, the condensation with CS 2 was reported solely in the case of 4,6-dimethyl-2-pyridone derivatives (Scheme B) and has not received further attention. Yet, the methylthio leaving group at the electrophilic site C2 on the cyclization product II would enable the access of more complex derivatives III by simple nucleophilic substitution.…”

Hetero Analogues of the Antimicrobial Alkaloids Cleistopholine and Sampangine

“…Tricyclic and tetracyclic aromatic systems containing thioether or sulfone moieties have been described as potent analogues of anthracyclines [6]. Some azaxanthenes (X = O) have been described to exhibit antiallergic, antiphlogistic and antiulcer activities [7], and numerous substituted azathioxanthones (X = S) have been described in patent literature, but without any information about biological activities [8]. A limited number of 4-substituted azaxanthones has been prepared by addition of Grignard reagents to the parent azaxanthone [9].…”