Journal ArticleDOI
Benzopyrans. Part 23. Nitrogen heterocycles fused with or linked to 1-benzopyran from 3-acyl-2-methyl-1-benzopyran-4-one
TLDR
The enamine (2) as discussed by the authors is a mixture of benzopyranone and dimethylformamide dimethyl acetal and on treatment with ammonia and hydroxylamine gives the fused pyridine 2-oxide (10), pyridinioacetamidate (11), and azepine (20), respectively.Abstract:
The enamine (2), prepared from the title benzopyranone (1; R2= H, Me, and Ph) and dimethylformamide dimethyl acetal, on treatment with ammonia and hydroxylamine gives the fused pyridine (5) and pyridine 2-oxide (10), respectively. Hydrazine, phenylhydrazine, and guanidine undergo initial 1,6-addition to the enamine (2) ultimately giving the pyrazoles (14) and (15), and the pyrimidine (17), respectively. The pyridinioacetamidate (11), prepared from the enamine (2; R2= Me and Ph) and acetohydrazide, thermolyses to the fused pyridine (5). A refluxing ethanolic solution of the enamine (2; R2= Me and Ph) with ethyl glycinate forms the ester (18) which on treatment with ethanolic sodium ethoxide produces the azepine (20).read more
Citations
More filters
Journal ArticleDOI
Synthesis of 3-alkenyl-2-arylchromones and 2,3-dialkenylchromones via acid-catalysed retro-Michael ring opening of 3-acylchroman-4-ones
TL;DR: 3-Acylchromones and 3-acylflavones undergo efficient conjugate reduction with NaBH 4 in pyridine to give the corresponding chroman-4-ones/flavanones in high yields in both regio- and chemoselective mode.
Journal ArticleDOI
Preparation and reactions of isoflavone heteroanalogs (a review)
TL;DR: Methods for preparation of 3-hetarylchromones, which are isoflavone heteroanalogs, and reactions of these compounds with either preservation or opening of the pyrone ring are reviewed in this article.
Journal ArticleDOI
Six-Membered Ring Systems: With O and/or S Atoms
John D. Hepworth,B. Mark Heron +1 more
TL;DR: In this article, a review of reaction chemistry and new ring synthetic methods for pyranones is presented, which covers work published in the calendar year 2010 and includes new ring synthesis methods for trioxanes, tetraoxane, dioxanes, trithianes and oxathianes.
Journal ArticleDOI
Total Synthesis of (±)-Oxalicumone C and Chiral Resolution and Elucidation of Its Absolute Configuration
TL;DR: The racemic total synthesis, the chiral resolution, and elucidation of the absolute configuration of the natural product oxalicumone C were investigated in this article, which was achieved by a synthetic strategy beginning with the synthesis of a 5-hydroxy-7-methylchromone precursor.