SCHEDULED MAINTENANCE
High-yield syntheses of dilithio-derivatives of furan, thiophen, N-methylpyrrole, 3-methylfuran, and 3-methylthiophen. Application of the method to 2-methylfuran, 2-methylthiophen, 2,5-dimethylfuran, 2,5-dimethylthiophen, benzo[b]furan, benzo[b]thiophen, pyrrole, and indole
Abstract
Conditions are established for the preparation in yields approaching quantitative of 2,5-dilithio-furan and -thiophen. The effects of changes in reaction conditions on the rates of hydrogen–lithium exchange for furan and thiophen have been investigated and are discussed in detail. The appearance of a 2,4-dilithio-intermediate, peculiar to N-methyl-pyrrole, has been explored, and optimum conditions are presented for the syntheses of both 2,4- and 2,5-intermediates. 3-Methylfuran and 3-melhylthiophen are similar to the parent heterocycles in their hydrogen–lithium exchange properties. The results of applying the procedure found to produce high yields of dilithio-products to a further eight heterocycles are described.
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