2,3,4-Trimethoxybenzaldehyde → 5-Methoxy-2-methyl-1-(2,3,4-trimethoxybenzylidene)-3-indenyl acetic acid

Beteiligte Stoffe

Reaktionsschritte

To a solution of methyl 5-methoxy-2-methyl-3-indenylacetate 8.7 g (0.037 mol) and 2,3,4-trimethoxybenzaldehyde, 7.99 g (1.1 equivalent) is added 16+ml (2.0+equivalents) of 25% methanolic sodium methoxide. The mixture is stirred at reflux under nitrogen for 2 hours. An equal volume of water is added dropwise and refluxing continues for 30 min. The solution is cooled, diluted with water and extracted with ether (3×). Residual ether is blown off with nitrogen, and then the aqueous solution is acidified with 50% glacial acetic acid. The precipitated product is collected and washed thoroughly with water. The crude product is crystallized to give 5-methoxy-2-methyl-1-(2,3,4-trimethoxybenzylidene)-3-indenyl-acetic acid. (R and R1 =H, R2 =OCH3, R3 and R4 =H, R5, R6 and R7 =OCH3, R8 =CH3, o=1, M=OH)

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