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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 major impact flavor compound of Wisteria sinensis has been synthesized from 2,4,5-trimethoxybenzaldehyde via scopoletin.
Abstract: 6-Methoxy-4H-1-benzopyran-7-ol 7 , a major impact flavor compound of Wisteria sinensis has been synthesized from 2,4,5-trimethoxybenzaldehyde 1 via scopoletin 3 . The synthetic sequence comprised (i) bisdemethylation of 2,4,5-trimethoxybenzaldehyde 1 , (ii) Wittig reaction with ethoxycarbonylmethylenetriphenylphosphorane, (iii) hydrogenation on palladium/carbon in glacial acetic acid, (iv) DIBAL-H reduction of the intermediate lactone and (v) dehydration of the lactol with anhydrous oxalic acid.
2 citations
Patent•
18 Jul 2003
TL;DR: In this paper, a new benzopyran compound capable of improving liquid crystal physical properties, by adding the compound to conventional liquid crystal compositions, was proposed, which is expressed by general formula (1) (X 1, X 2, X 3, Z, and R are each an alkyl, H, a halogen or cyano; Y is H or methyl; A is 1,4-phenylene of which the H may be substituted by F or 1, 4- cyclohexylene which is not substituted; W is a single bond,-C
Abstract: PROBLEM TO BE SOLVED: To provide a new benzopyran compound capable of improving liquid crystal physical properties, by adding the compound to conventional liquid crystal compositions. SOLUTION: This benzopyran compound is expressed by general formula (1) (X 1 , X 2 , X 3 , Z, and R are each an alkyl, H, a halogen or cyano; Y is H or methyl; A is 1,4-phenylene of which the H may be substituted by F or 1,4- cyclohexylene which is not substituted; W is a single bond,-COO- or the like; and n is 0 or 1). COPYRIGHT: (C)2003,JPO
2 citations
TL;DR: The photochemical conversion of 4,4,7,7-tetramethyl into 3,3,6,6-tETramethyl-3,5, 6,7 -tetrahydrobenzofuran-4(2H)-one (4) in methanol does not - as previously assumed - proceed by decarbonylation of the primarily formed acyl-vinyloxy biradical 2 as mentioned in this paper.
Abstract: The photochemical conversion of 4,4,7,7-tetramethyl-4,6,7,8-tetrahydro-2H-benzopyran-2,5(3H)-dione (1) into 3,3,6,6-tetramethyl-3,5,6,7-tetrahydrobenzofuran-4(2H)-one (4) in methanol does not - as previously assumed - proceed by decarbonylation of the primarily formed acyl-vinyloxy biradical 2 This conclusion results from the finding that C-2, i e the CH2 group, of benzofuranone 4 stems from the solvent Similar observations were made for other benzopyrandiones 15 A reaction sequence consisting of (a) ketene elimination from 2 with formation of 2-isopropylidene-5,5-dimethyl-1,3-cyclo-hexanedione and (b) light-induced (reductive) H and CH2OH addition to this intermediate followed by cyclization and dehydration to 4, is proposed for the conversion 14
2 citations
TL;DR: In this paper, the linear (65-81%) and angular (51-60%) bioactive natural and unnatural benzopyran derivatives are produced exclusively in one step and described via phenol-keto resonance.
Abstract: Remarkably tuned regioselectivities are obtained in the condensation of 3,5-dihydroxyphthalide (1) with several α,β-unsaturated aldehydes using DBU and neutral conditions. The linear (65-81%) and angular (51-60%) bioactive natural and unnatural benzopyran derivatives are produced exclusively in one step and are described via phenol-keto resonance.
2 citations