A General Synthesis of Substituted Indoles from Cyclic Enol Ethers and Enol Lactones

[reaction: see text] X = CH2, C[double bond]O, R2 = H, alkyl. A general method was developed for the one-pot synthesis of highly functionalized indoles from simple, commercially available aryl hydrazines and cyclic enol ethers. Enol lactones were also used as substrates, affording substituted indole acetic acid or indole propionic acid derivatives. This procedure affords 2,3-disubstituted indoles as single regioisomers from the appropriately substituted enol ether or enol lactone. This method was highlighted in the efficient synthesis of the antimigraine drug sumitriptan and the antiinflammatory drug indomethacin.

Intramolecular addition of benzylic radicals onto ketenimines. Synthesis of 2-alkylindoles

The inter- and intramolecular addition of free radicals onto ketenimines is studied. All the attempts to add intermolecularly several silicon, oxygen or carbon centered radicals to N-(4-methylphenyl)-C,C-diphenyl ketenimine were unsuccessful. In contrast, the intramolecular addition of benzylic radicals, generated from xanthates, onto the central carbon of a ketenimine function with its N atom linked to the ortho position of the aromatic ring occurred under a variety of reaction conditions. These intramolecular cyclizations provide a novel radical-mediated synthesis of 2-alkylindoles.

A convergent approach to 3-substituted-5-methoxyindoles. Application to the synthesis of melatonin [correction]

A convergent, radical based synthesis of 5-methoxyindoles including melatonin is described.