Revisiting the three component synthesis of isoxazolo[5,4-b]pyridines, 4-aryl-3,7,7-trimethyl-isoxazolo[5,4-b]quinolin-5(6H)-ones and related heterocycles

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• 作者：Anthony R. Lingham^a ; ^{anthony.lingham@rmit.edu.au} ; John A. Hawley^b ; Tamar Greaves^a ; Neale Jackson^a ; Frank Antolasic^a ; Helmut M. Hü ; gel^a ;
• 关键词：Multicomponent microwave synthesis ; Knoevenagel ; Isoxazolopyridines ; Isoxazoloquinolinones ; Tetrahydroacridones
• 刊名：Polyhedron
• 出版年：2016
• 出版时间：14 December 2016
• 年：2016
• 卷：120
• 期：Complete
• 页码：175-179
• 全文大小：985 K
• 卷排序：120

文摘

The one-step three-component microwave assisted synthesis between aromatic aldehydes with tetronic acid or indan-1,3-dione readily formed the Knoevenagel adducts that underwent addition of 3-methylisoxazol-5-amine 1 to form the isoxazolo[5,4-b]pyridine products 8[a,b,d,e,g] in 67–90% yield. The multicomponent reaction using dimedone formed the respective addition products 4-aryl-3,7,7-trimethyl-isoxazolo[5,4-b]quinolin-5(6H)-ones 8[c,f,h] (36–79%). In contrast, the sonication of an aryl aldehyde and dimedone with an equivalent amount of 2-hydroxyammonium formate exclusively generated the Knoevenagel adduct 4c via hydro-4c. When microwaved either with 3-amino-5-methylisoxazole 1 or 3,4,5-trimethoxyaniline 14 in ethanoic acid–ethylacetate (1:1), tetrahydroacridones 15[a,b] formed in high yields (88–92%). Importantly, this two-step reaction sequence generates highly reproducible and pure products.