Topic
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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TL;DR: In this paper, the synthesis of substituted 7,7-diphenyl-7H-pyrano[3,2-e]benzazoles 2a-f and 7, 7-Diphenymethyl-7 H-Pyrano [2,3-g]benzmanazoles 4a-d is described.
Abstract: The synthesis of substituted 7,7-diphenyl-7H-pyrano[3,2-e]benzazoles 2a-f and 7,7-diphenyl-7H-pyrano[2,3-g]benzazoles 4a-d is described. Thus, suitable titanium(IV) phenolates reacted with β-phenylcinnamaldehyde in refluxing aprotic non-polar solvents. Electrocyclisation of o-quinone allides generated in situ gives regiospecifically the title compounds. Stoichiometric amounts of heterocyclic phenol, titanium tetraethoxide and the carbonyl compound, have been found to give better results. In this series, substitution on the α position leads to the formation of the regioisomer. The method could be also extended to the formation of 8,8-diphenyl-8H-pyrano[2,3-e]benzazole 8. A side reaction between the desired pyran and a second molecule of heterocyclic phenol was observed. This condensation product 9 was isolated and characterized in the case of the imidazole derivative, and a mechanism for its formation is proposed.
1 citations
TL;DR: The reaction between cyclohexanone enamines and a variety of benzylidene ketones gives a dihydropyran derivative in each case as discussed by the authors, which on heating readily rearranges into isomeric enamino-ketones.
Abstract: The reaction between cyclohexanone enamines and a variety of benzylidene ketones gives a dihydropyran derivative in each case. The benzopyrans from reactions of 1 -piperidinocyclohexene with chalcone and with dibenzylideneacetone are unstable and on heating readily rearrange into isomeric enamino-ketones (6) and (10). Recyclisation of 2-phenyl-2-(2-piperidinocyclohex-2-enyl)ethyl styryl ketone (10) gives 1,4-diphenyl-7b-piperidinoperhydrocyclobuta[de]naphthalen-2-one (11).
1 citations
TL;DR: In this paper, a DMF-optimized reaction conditions using DMF as the solvent was developed to obtain the desired benzopyrans (III) exclusively, and the results showed that the DMF can achieve the desired results.
Abstract: Optimized reaction conditions using DMF as the solvent are developed to obtain the desired benzopyrans (III) exclusively.
1 citations
TL;DR: In this paper, 2.2-Styryl and 2.3-pyranobenzopyrones via H-abstraction were obtained for photolysis in benzene and MeOH, respectively.
1 citations
TL;DR: In this article, an intramolecular conjugate addition of allyloxy anions to diphenylphosphinoyl-substituted benzene rings is described.
Abstract: A new synthetic method for the preparation of multisubstituted benzopyrans that involves an intramolecular conjugate addition of allyloxy anions to diphenylphosphinoyl-substituted benzene rings is described. The intermediate anion is trapped with electrophiles providing benzopyrans that are readily oxidized with O 2 to intermediates containing a peroxide that is easily converted into benzopyran-2-ones (i.e. coumarins).
1 citations