Stephen B. Bostock

The reaction of hydroquinone and monosubstituted hydroquinones with dimethyl chloromalonate

Hydroquinone and monosubstituted hydroquinones free from –I,–M groups react with dimethyl chloromalonate in methanolic sodium methoxide solution to give 2-oxido-benzo[b]furan derivatives (1). The mechanism of this base catalysed C-alkylation is interpreted in terms of initial mono-O-alkylation followed by fragmentation and 1,4-addition of dimethyl sodiomalonate to the nascent 1,4-benzoquinone so formed. The procedure furnishes, in moderate to high yield, products which cannot be prepared readily by direct nucleophilic addition to 1,4-benzoquinones.

Reaction of phthalic anhydride with ethyl cyanoacetate: a route to the 2H-indeno[2,1 -c]pyridine-1,9-dione, 2H-indeno[2,1-c]pyridine-3,9-dione, 2H-indeno[2,1-c]pyridazine-3,9-dione, and indeno[2,1-c]pyran-1,9-dione systems

The Knoevenagel condensation of phthalic anhydride with ethyl Cyanoacetate gives (Z)-ethyl 2-carbamoyl-8-cyano-3-hydroxybenzofulvene-8-carboxylate (2) in good yield. This compound provides a ready entry into the 2H-indeno[2,1-c]pyridine-1,9-dione, 2H-indeno[2,1-c]pyridine-3,9-dione, 2H-indeno[2,1-c]pyridazine-3,9-dione, and indeno[2,1-c]pyran-1,9-dione systems.