| Popis: |
The formylation of thieno[3,4-b]thiophene gives a mixture of 4-formyl- and 6-formyl-thieno[3,4-b]thiophene in a ratio of 70 : 30. Lithiation followed by formylation of the resulting organolithium compounds changes this ratio to 20 : 80. The formylation of methyl thieno[3,4-b]thiophene-2-carboxylate has been shown to give the 4- and 6-substituted isomers in a 50 : 50 ratio. The structures of the substitution products were established by oxidation and desulfurization experiments and by PMR spectroscopy. |
