TY - JOUR
T1 - Preparation of cis- and trans-2,3-Dimethyl-2,3-dihydrobenzofurans and Related Compounds. Cyclizations Involving Oxonium Ions
AU - Brust, David P.
AU - Tarbell, D. Stanley
AU - Hecht, Sidney M.
AU - Hayward, Edward C.
AU - Colebrook, L. D.
PY - 1966/7
Y1 - 1966/7
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-l-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-l-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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U2 - 10.1021/jo01345a029
DO - 10.1021/jo01345a029
M3 - Article
AN - SCOPUS:0005132210
SN - 0022-3263
VL - 31
SP - 2192
EP - 2201
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
IS - 7
ER -