Dimerization/Elimination of β-Styrylmalonates under Action of TiCl 4 .

A new type of dimerization of dimethyl (β-styryl)malonates in the presence of TiCl 4 accompanied by elimination of a methanol molecule was discovered. Selective methods for the synthesis of substituted trimethyl 4-hydroxy-[1,1'-biaryl]-3,3,5(2 H )-tricarboxylates and trimethyl 7-hydroxy-9,10-dihydro-5,9-methanobenzo[8]annulene-6,8,8(5 H )-tricarboxylates were developed. The regularities of the occurring processes were determined and a similar reaction of β-styrylmalonate with benzylidenemalonate in the presence of TiCl 4 was performed in the scope of the suggested mechanism.