The irradiation of chromone-2-carboxylicesters resulted in the stereo- and regioselective formation of C2 chiral anti-HH dimers from the triplet excited state. On the contrary, photolysis in the solid-state gave anti-HT dimers exclusively controlled by molecular arrangement in the crystal.
Studies on the chemical reactivity of 1H-benzimidazol-2-ylacetonitrile towards some 3-substituted chromones: synthesis of some novel pyrido[1,2-a]benzimidazoles
作者:Magdy A. Ibrahim
DOI:10.1016/j.tet.2013.06.011
日期:2013.8
A simple and convenient synthesis of a novel series of pyrido[1,2-a]benzimidazoles was efficiently achieved from the condensation reactions of 1H-benzimidazol-2-ylacetonitrile (1) with some 3-substituted chromones, chromone-3-carboxylic acids, chromone-3-carboxamides, ethyl chromone-3-carboxylates and chromone-3-carbonitriles. Reaction of compound 1 with 2-aminochromone-3-carboxaldehydes produced
1 H-苯并咪唑-2-基乙腈(1)与某些3-取代的色酮,色酮-3-羧基的缩合反应可有效地简单,方便地合成一系列新的吡啶并[1,2- a ]苯并咪唑类化合物酸,苯甲酸酯-3-甲酰胺,苯甲酸酯-3-羧酸盐和苯甲酸酯-3-甲腈。化合物1与2-氨基色酮-3-羧醛的反应产生2-氨基-3-(1H-苯并咪唑-2-基)铬诺[2,3- b ]吡啶。还讨论了反应机理和光谱数据。
Reaktionen an Heterocyclen mit 2-Acyl-2-propenon-Teilstruktur, 3. Mitt. Pyrido[3,2-c]cumarine aus 3-substituierten 1-Benzopyranen und Enaminen
作者:Dieter Heber
DOI:10.1002/ardp.19873200505
日期:——
der aus 4‐Oxo‐4H‐chromen‐3‐carboxaldehyden 1 und Enaminen 2 bzw. 3 darstellbaren 5‐Hydroxy‐5H‐[1]benzopyrano[4,3‐b]pyridine 4 und 5 führt zu den Pyrido [3,2‐c]‐cumarinen 6 und 7, die auch direkt aus der 4‐Oxo‐4H‐chromen‐3‐carbonsäure (8) sowie ihrem Ethylester 9 zugänglich sind. Das Pyridocumarin 6a erhält man aus der Chromanon‐Mannichbase 14 über C‐Alkylierung des Enamins 2, Cyclisierungund Oxidation
Enantioselective Access to Tetrahydroxanthones via Copper-<i>bis</i>(oxazoline)-Catalyzed [4 + 2] Cycloaddition
作者:Jonathan W. Attard、Julia R. Noel、Yong Guan、Anita E. Mattson
DOI:10.1021/acs.orglett.3c00612
日期:2023.4.14
Highly enantioselective access to tetrahydroxanthone compounds was achieved through copper-bis(oxazoline)-catalyzed [4 + 2] cycloaddition of chrom-4-one dienophiles and Danishefsky’s diene. Oxo-dihydroxanthone (enone) adducts, containing a quaternary stereocenter, are generated in up to 98% yield and 89% ee. Cycloadducts are utilized in the synthesis of tetrahydroxanthones, featuring a novel organotin-mediated