Easy synthesis of 2,4-dialkyl substituted phenols and anisoles from p-bensoquinone
摘要:
The reaction of p-benzoquinone (1) with several organolithium compounds (methyl-, ethyl-, n-butyl, phenyllithium) leads directly, after acid hydrolysis, to the corresponding 2,4-dialkylphenols 4a-d, resulting from a rearrangement/aromatization process of the corresponding intermediate diols 3. The use of two different alkyllithium reagents leads to the mixed products 4e.f. Alternatively, the same results are obtained treating the crude isolated diols 3 with a catalytic amount of concentrated sulfuric acid. Applying this last methodology to the diethers 2, 2,4-dialkylanisoles 8 are obtained. A possible mechanism is proposed.
Stereoselective two-step chemical preparation of 1,4-dialkyl-1,4-dimethoxycyclohexa-2,5-dienes
作者:Francisco Alonso、Miguel Yus
DOI:10.1016/s0040-4020(01)89749-0
日期:1991.8
phenyllithium) led after hydrolysis with water to the corresponding crude diols 4 which were successively treated with sodium hydride and methyl iodide yielding the expected 1,4-dialkyl-1,4-dimethoxycyclohexa-2,5-dienes 2a-d in a stereoselective manner. The use of a tandem process with two different organolithium reagents followed by methylation by the same procedure yielded stereoselectively the mixed 1-alkyl-4-alkyl'