Preparation of cis- and trans-2,3-dimethyl-2,3-dihydrobenzofurans and related compounds. Cyclizations involving oxonium ions

David P. Brust, D. Stanley Tarbell, Sidney Hecht, Edward C. Hayward, L. D. Colebrook

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Abstract

Crotyl 2,4-dichloro-5-methylphenyl ether (A) gave a mixture of the expected product, 2,4-dichloro-5-methyl-6-(α-methylallyl)phenol (B-2), and 2,4-dichloro-3-methyl-6-(α-methylallyl)phenol (C-2) when refluxed in dimethylaniline. Compound B-2 was converted to 2-methyl-6-oxo-1-cyclohexene(2-propionic acid) (H) by methylation, oxidation with permanganate-periodate, reduction with lithium-liquid ammonia, and acid hydrolysis. The phenol B-2 and its methyl ether were cyclized by concentrated sulfuric acid to cis- and trans-2,3-dihydro-2,3,4-trimethyl-5,7-dichlorobenzofurans (J and I); these were separated, configurations were assigned, and the equilibration of the cis and trans forms studied. Treatment of B-2 and its methyl ether with ICl gave the cis- and trans-iodomethyl compounds, M and L, whose configurations have been related to those of the dimethyl compounds J and I. J2H-3H for the cis- and trans-2,3-dihydrobenzofurans have been measured and compared with calculated values.

Original languageEnglish (US)
Pages (from-to)2192-2201
Number of pages10
JournalJournal of Organic Chemistry
Volume31
Issue number7
StatePublished - 1966
Externally publishedYes

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Cyclization
Phenol
Methyl Ethers
Ions
Anisoles
Methylation
Lithium
Ammonia
Hydrolysis
Oxidation
Acids
Liquids
coumaran
hydronium ion

ASJC Scopus subject areas

  • Organic Chemistry

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Preparation of cis- and trans-2,3-dimethyl-2,3-dihydrobenzofurans and related compounds. Cyclizations involving oxonium ions. / Brust, David P.; Tarbell, D. Stanley; Hecht, Sidney; Hayward, Edward C.; Colebrook, L. D.

In: Journal of Organic Chemistry, Vol. 31, No. 7, 1966, p. 2192-2201.

Research output: Contribution to journalArticle

Brust, David P. ; Tarbell, D. Stanley ; Hecht, Sidney ; Hayward, Edward C. ; Colebrook, L. D. / Preparation of cis- and trans-2,3-dimethyl-2,3-dihydrobenzofurans and related compounds. Cyclizations involving oxonium ions. In: Journal of Organic Chemistry. 1966 ; Vol. 31, No. 7. pp. 2192-2201.
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abstract = "Crotyl 2,4-dichloro-5-methylphenyl ether (A) gave a mixture of the expected product, 2,4-dichloro-5-methyl-6-(α-methylallyl)phenol (B-2), and 2,4-dichloro-3-methyl-6-(α-methylallyl)phenol (C-2) when refluxed in dimethylaniline. Compound B-2 was converted to 2-methyl-6-oxo-1-cyclohexene(2-propionic acid) (H) by methylation, oxidation with permanganate-periodate, reduction with lithium-liquid ammonia, and acid hydrolysis. The phenol B-2 and its methyl ether were cyclized by concentrated sulfuric acid to cis- and trans-2,3-dihydro-2,3,4-trimethyl-5,7-dichlorobenzofurans (J and I); these were separated, configurations were assigned, and the equilibration of the cis and trans forms studied. Treatment of B-2 and its methyl ether with ICl gave the cis- and trans-iodomethyl compounds, M and L, whose configurations have been related to those of the dimethyl compounds J and I. J2H-3H for the cis- and trans-2,3-dihydrobenzofurans have been measured and compared with calculated values.",
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T1 - Preparation of cis- and trans-2,3-dimethyl-2,3-dihydrobenzofurans and related compounds. Cyclizations involving oxonium ions

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N2 - Crotyl 2,4-dichloro-5-methylphenyl ether (A) gave a mixture of the expected product, 2,4-dichloro-5-methyl-6-(α-methylallyl)phenol (B-2), and 2,4-dichloro-3-methyl-6-(α-methylallyl)phenol (C-2) when refluxed in dimethylaniline. Compound B-2 was converted to 2-methyl-6-oxo-1-cyclohexene(2-propionic acid) (H) by methylation, oxidation with permanganate-periodate, reduction with lithium-liquid ammonia, and acid hydrolysis. The phenol B-2 and its methyl ether were cyclized by concentrated sulfuric acid to cis- and trans-2,3-dihydro-2,3,4-trimethyl-5,7-dichlorobenzofurans (J and I); these were separated, configurations were assigned, and the equilibration of the cis and trans forms studied. Treatment of B-2 and its methyl ether with ICl gave the cis- and trans-iodomethyl compounds, M and L, whose configurations have been related to those of the dimethyl compounds J and I. J2H-3H for the cis- and trans-2,3-dihydrobenzofurans have been measured and compared with calculated values.

AB - Crotyl 2,4-dichloro-5-methylphenyl ether (A) gave a mixture of the expected product, 2,4-dichloro-5-methyl-6-(α-methylallyl)phenol (B-2), and 2,4-dichloro-3-methyl-6-(α-methylallyl)phenol (C-2) when refluxed in dimethylaniline. Compound B-2 was converted to 2-methyl-6-oxo-1-cyclohexene(2-propionic acid) (H) by methylation, oxidation with permanganate-periodate, reduction with lithium-liquid ammonia, and acid hydrolysis. The phenol B-2 and its methyl ether were cyclized by concentrated sulfuric acid to cis- and trans-2,3-dihydro-2,3,4-trimethyl-5,7-dichlorobenzofurans (J and I); these were separated, configurations were assigned, and the equilibration of the cis and trans forms studied. Treatment of B-2 and its methyl ether with ICl gave the cis- and trans-iodomethyl compounds, M and L, whose configurations have been related to those of the dimethyl compounds J and I. J2H-3H for the cis- and trans-2,3-dihydrobenzofurans have been measured and compared with calculated values.

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