Topic
Benzopyran
About: Benzopyran is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 15235 citations.
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TL;DR: In this article, a general synthesis of the novel 2-aryl-3-chloro-2,3-dihydro-3,nitro-4H-1-benzopyran-4-ones was described.
Abstract: 2-Aryl-3-nitro-4H-1-benzopyran-4-ones (or 3-nitroflavones) 3 are conveniently prepared in good yields using a two-step approach starting from 2-aryl-3-chloro-3,4-dihydro-4-hydroxy-3-nitro-2H-1-benzopyrans 1. A general synthesis of the novel 2-aryl-3-chloro- 2,3-dihydro-3-nitro-4H-1-benzopyran-4-ones 2 employed as intermediates in the procedure is described
2 citations
Patent•
12 Aug 2015
TL;DR: In this article, a method of tetrahydro benzopyran derivatives is described, which adopts cyclodextrin as a catalyst, adopts aromatic aldehyde, dimedone and malononitrile as raw materials and adopts water, ethanol or methanol as a solvent.
Abstract: A preparing method of tetrahydro benzopyran derivatives is disclosed. The method adopts cyclodextrin as a catalyst, adopts aromatic aldehyde, dimedone and malononitrile as raw materials and adopts water, ethanol or methanol as a solvent. A reaction is performed at 15-30 DEG C, and the tetrahydro benzopyran derivatives can be prepared by recrystallization or column chromatography separation after the reaction is finished. The method is mild in reaction conditions, short in process steps, simple and convenient in operation, low in cost and high in yield, and has a good industrial application prospect.
2 citations
TL;DR: The extent of diastereotopy depends upon their nature and the separation of methylene groups from the chiral centre; the effect is greatly influenced by the pi-electron system of the substituent.
2 citations
01 Jan 2009
TL;DR: In this article, an efficient synthesis route to dibenzoxanthene, xanthene and benzopyran derivatives from reaction of divergent aldehydes with �-naphthol, dimedone and ethyl cyanoacetate under solvent-free conditions by indium chloride as a relative inexpensive, eco-friendly, easy available, nonvolatile, nonexplosion, thermally robust, recyclable and easy to handle catalyst at 90°C with good to excellent yields is described.
Abstract: An efficient synthesis route to dibenzoxanthene, xanthene and benzopyran derivatives from reaction of divergent aldehydes with �-naphthol, dimedone and ethyl cyanoacetate respectively under solvent-free conditions by indium chloride as a relative inexpensive, eco-friendly, easy available, non-volatile, non-explosion, thermally robust, recyclable and easy to handle catalyst at 90°C with good to excellent yields is described. Unenhanced reaction times, simple reaction protocol and work-up, improved synthesis of these materials in the presence of this heterogeneous catalyst.
2 citations
Patent•
14 Feb 1984
TL;DR: In this paper, a compound (salt) shown by the formula I (one of X and Y is O, and the other is methylene or carbonyl; A is H, halogen, methyl, acetyl, cyanoethyl, etc.).
Abstract: NEW MATERIAL:A compound (salt) shown by the formula I (one of X and Y is O, and the other is methylene or carbonyl; A is H, halogen, methyl, acetyl, cyanoethyl, etc.; B is H, halogen, methyl, alpha-cyanoethyl, methoxycarbonylmethyl, etc.; C is H, halogen, methyl, methoxycarbonylmethyl, etc.; D and E are H, halogen, or methyl; with the proviso that the case wherein X is O, Y is carbonyl, and A-E are H is omitted). EXAMPLE:9H-Thieno[3,2-b][1] benzopyran-2-propionic acid. USE:An antiphlogistic. PROCESS:For example, a 3-alkoxythiophene is reacted with o-anisoyl chloride to give a compound shown by the formula II, which is subjected to ring closure to give 9H-thieno[3,2-b][1] benzopyran shown by the formula III, which is further acetylated, converted into a nitrile group, and hydrolyzed, to give a compound shown by the formula I .
2 citations