Efficient Base-Catalyzed 5-exo-dig Cyclization of Carbonyl Groups on Unactivated Alkynyl-Quinolines: An Entry to Versatile Oxygenated Heterocycles Related to the Furoquinoline Alkaloids Family

Abstract

An efficient 5-exo-dig cyclization was observed when TMS-protected alkynyl-quinolines bearing a carbonyl group were submitted to a mixture of an alcohol (alkyl-OH, diol, amino alcohol) with an inorganic base (K 2 CO 3 ). The cyclization process seems to go through the deprotection of the TMS group prior to the cyclization step. The dihydrofuroquinoline derivatives formed are structurally related to the well-known furoquinoline alkaloids family. The scope and limitations of this reaction have also been studied with diverse bases and various alkynyl and carbonyl derivatives.