jeudi 15 février 2007


Side reactions in organic chemistry can be considered as a failure in a target oriented synthesis, but it can be a valuable source a inspiration for the design of new methodologies.
In 2004, Baldwin and coll. tried to synthesize the 5,5',6,6'-tetrahydroxy-3,3'-biindolyl, a potent antioxidant, he proposed as key step a bis-cyclization of the two 2-aminoaryl substituents on the furan (as 1,4-dialdheyde precursor).

Cyclization was attempted with para-toluenesulfonic acid in benzene, and lead to the formation of a 3-arylquinoline in poor 25% yield along with the starting material.

Finally, the 3,3'-biindole has been synthesized by a palladium catalyzed homocoupling reaction from the corresponding 3-iodoindole.

For the mechanism of the quinoline formation and other informations see:

Tetrahedron 60 (2004) 3695–3712

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