Stereoselective synthesis of cyclohexa-2,4-dien-1-ones and cyclohex-2-en-1-ones from phenols
摘要:
A convenient synthetic method for the synthesis of substituted cyclohex-2-en-1-ones by the direct alkylation of phenols has been developed. Furthermore, enantiomerically enriched 2,6-dimethyl-6-(3-methylbut-2-enyl)-cyclohexa-2,4-dienone was prepared by the deprotonation of 2,6-dimethylphenol with a sparteine-lithium complex followed by alkylation with 1-chloro-3-methylbut-2-ene. 2,6-Dimethyl-6-(3-methyl-but-2-enyl)-cyclohex-2-enone was prepared from the corresponding cyclohexa-2,4-dien-1-one by selective hydrogenation of the 4,5-double bond. The method was extended to 2-methyl-naphthalen-1-ol and 1-methyl-naphthalen-2-ol resulting in 2-(R)methyl-2-(3-methylbut-2-enyl)-2H-naphthalen- 1-one and 1-(S)-methyl-1-(3-methylbut-2-enyl)-1H-naphthalen-2-one, respectively. (c) 2006 Elsevier Ltd. All rights reserved.
tetrachloride to conjugated 1,3-dienes such as 1,3-butadiene, 1,3-pentadiene, isoprene, 1,3-cyclohexadiene and 1,3-cyclooctadiene proceeded smoothly under mild conditions in the presence of dichlorotris(triphenylphosphine)ruthenium(II) to give the corresponding 1,4-addition products as 1:1 adducts in excellent yields.