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Benzopyrans

About: Benzopyrans is a research topic. Over the lifetime, 694 publications have been published within this topic receiving 8830 citations.


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Journal ArticleDOI
TL;DR: In this paper, 3-, 4-, or 6-Halo-2H-1-benzopyrans are prepared by reacting the haloge-nated coumarins with lithium, magnesium or aluminium organometallics, and further thermal cyclization of the resulting o-hydroxycinnamyl alcohols.
Abstract: 3-, 4-, or 6-Halo-2H-1-benzopyrans are prepared by reacting the haloge- nated coumarins with lithium, magnesium or aluminium organometallics, and further thermal cyclization of the resulting o-hydroxycinnamyl alcohols. The method is not applicable for 3-halo-2H-1-benzopyrans with no-substituents on C-2. The 3-, or 4-halo-2H-1-benzopyrans derivatives give non-metallated products when the species obtained are subjected to metal-halogen interchange with butyllithium, whereas the 6-bromo derivatives afford 6-lithium-2H-1-benzopyrans

7 citations

Patent
Lee Cheuk M1
25 May 1972
TL;DR: In this paper, the basic carbonates and carbamates of benzopyrans represented by the formula are represented as the formula, where n is 1 or 2, n is O or NH, y is an integer from 2-6, and R4 and R5 each are hydrogen or loweralkyl.
Abstract: WHEREIN N IS 1 OR 2; R1 is hydrogen or loweralkyl; R2 is loweralkyl; R3 is alkyl or cycloalkyl; X is O or NH; y is an integer from 2-6; and R4 and R5 each are hydrogen or loweralkyl; or R4 and R5 taken together form a 5- or 6-membered heterocyclic ring and the acid addition salts thereof. Basic carbonates and carbamates of benzopyrans represented by the formula

7 citations

Journal ArticleDOI
TL;DR: Pyrrolidine, morpholine and piperidine derived Mannich bases of types 1-3 react with acetone, propionaldehyde and butyraldehyde to form 2-methyl and 3-methylbenzopyrans of types 4-8 as mentioned in this paper.

7 citations

Journal ArticleDOI
TL;DR: In this article, the reactions of 7-methoxy-2-phenyl-2H-1-benzopyran with lead(IV) acetate also gave the corresponding benzofuran and cyclohexadienone.
Abstract: The reactions of 7-methoxy-2-phenyl-2H-1-benzopyran and 7-methoxy-2-phenyl-4H-1-benzopyran with lead(IV) acetate gave 2-benzoyl-6-methoxybenzofuran and 6-acetoxy-3-methoxy-6-(3-oxo-3-phenyl-1 -propenyl)-2,4-cyclo-hexadien-1-one. The reactions of 7-methoxy-2-(p-methoxy-phenyl)-2H-1-benzopyran and 7-methoxy-2-(p-methoxyphen-yl)-4H-1-benzopyran with lead(IV) acetate also gave the corresponding benzofuran and cyclohexadienone. The reaction pathway is discussed.

7 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
20229
20214
20203
20192
20186