Synthesis of Prenylated Indoles

Article abstract of DOI:10.1021/jo00362a031

Interaction of magnesium indolates and allyl oxides in the presence of bis(triphenylphosphine)nickel dichloride results in indole β-allylation, except in cases involving highly substituted indoles and allyl alcohols.This method permits the β-prenylation of indole and α-prenylation of ketones (by way of their magnesium enaminates).Base-induced interaction of ethynyldimethylcarbinyl chloride and indole under a variety of conditions yields β-(β,β-dimethylvinyl)quinoline as well as variously dehydroprenylated indoles. α-Lithiation of N-(benzenesulfonyl)indole followed by treatmentwith prenyl bromide or β,β-dimethylacrylyl chloride produces α-prenyl- or α-oxoprenylidole derivatives, the sodium amalgam reduction of the former of which yields α-prenylidole.Interaction of β-cuprated N-(benzenesulfonyl)indole with the same halides followed by reduction affords β-prenylindole and β-oxoprenylindole, the latter also being the product of the reaction of magnesium indolate and the acid chloride.Lithium aluminum hydride reduction of 1-(benzenesulfonyl)-3-oxoprenylindole affords an alcohol, whose base hydrolysis produces β-dehydroprenylindole, a compound whose dimerization has led previously to naturally occuring yuehchukene.