Methyl 3-aryl-3-hydroxy-2-methylene propionates react with phenols, 2-naphtol, 1,4-dihydroxybenzene, 2,3-dihydroxynaphtalene and 2,7-dihydroxynaphtalene in the presence of silica gel-supported ZnBr2 or FeCl3 to give 3-arylidene-3,4-dihydro coumarins or 3-methylene-3,4-dihydrocoumarins.
Foucaud Andre, Brine Nourdine, Synth. Commun, 24 (1994) N 20, S 2851-2861
作者:Foucaud Andre, Brine Nourdine
DOI:——
日期:——
Trifluoroacetic acid catalyzed and thermal rearrangement ofα- aryloxymethyl cinnamic acids.
Severalα- aryloxymethyl cinnamic acids 1 have been rearranged in refluxing trifluoroacetic acid (TFA). The thermalrearrangement of the same acids in Polyethylene glycol - 200 (PEG - 200) has also been investigated.
Either [1,3]- or [3,3]-sigmatropic rearrangements were selectively accessed by controlling the reaction temperature in the gold(III)-catalyzed tandem rearrangement/cyclization of (E)-2-(aryloxymethyl)alk-2-enoates to afford diversely substituted 3,4-dihydrocoumarin derivatives in moderate to good yields and in excellent regioselectivity.