Synthesis of highly substituted 3-arylideneindolin-2-ones

3-Arylideneindolin-2-ones are an attractive structural class in drug development, including registered drugs and drug candidates for treatment of cancer, Alzheimer's disease, infections and others. While residues at C-5 and C-7 are easily introduced by electrophilic substitution reactions, position 4 is much less accessible. Here we describe a novel and effective synthesis of highly substituted 3-arylideneindolin-2-ones with flexible modification at C-4. Starting from 1,2-dichloro-3-nitrobenzene a central building block, a trihalogenated indolin-2-one, could be prepared in 6 high yielding steps. Subsequent modification of position 4 and 3 of this building block provided a library of highly substituted 4-substituted 3-arylidene-6,7-dichloroindolin-2-ones. This 8 step synthetic sequence utilized preferably precipitation and washing processes as method of purification.

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