An efficient and versatile tandem process of acetalization and cycloisomerization reactions has been developed for the reactions of 1-alkynyl-2-carbonylquinoline substrates. The reaction occurs thanks to Au(I) and Ag(I) catalysis. Silver(I) catalysis has been extensively studied (11 different silver species) on a broad range of quinoline derivatives (variation of alkyne substituent, of carbonyl function
Efficient Base-Catalyzed 5-<i>exo</i>-dig Cyclization of Carbonyl Groups on Unactivated Alkynyl-Quinolines: An Entry to Versatile Oxygenated Heterocycles Related to the Furoquinoline Alkaloids Family
作者:Philippe Belmont、Thomas Godet、Johann Bosson
DOI:10.1055/s-2005-918953
日期:——
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 (K2CO3). 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.
Silver-catalyzed tandem acetalization and cycloisomerization reactions were found to lead to various furoquinolines, and a nitrogen effect was noticed for AgOTf reactivity, since the cyclization mode switched from 6-endo-dig to 5-exo-dig; from these observations silver imidazolate polymer is proposed as a stable silver catalyst.
An Efficient and Simple Aminobenzannulation Reaction: Pyrrolidine as a Trigger for the Synthesis of 1-Amino-acridines
作者:Philippe Belmont、Tahar Belhadj
DOI:10.1021/ol050380z
日期:2005.4.1
A new aminobenzannulation methodology has been developed and applied successfully to the synthesis of 1-amino-acridines. The key and last step goes through an enamine intermediate that was detected in some cases. When pyrrolidine and powdered 4 angstrom molecular sieves were used, the enamine synthesis and the aminobenzannulation step took place subsequently, whereas for other secondary amines, neutral Al2O3 or PtCl2 catalysis was necessary.
A New Route to Acridines: Pauson-Khand Reaction on Quinoline-Bearing 1-En-7-ynes Leading to Novel Tetrahydrocyclopenta[<i>c</i>]acridine-2,5-diones
作者:Philippe Belmont、Amaury Patin
DOI:10.1055/s-2005-870016
日期:——
Efficient Pauson-Khand reactions on quinolines bearing 1-en-7-ynes features gave tetrahydrocyclopenta[c]acridine derivatives. The quinoline intermediates were obtained in two steps: a Sonogashira reaction with functionalized alkynes (TMS, Bu, Ph, CHB 2 OTHP) followed by a Grignardreaction with allylmagnesiumbromide. The sequence provides new acridine structures in four high yielding steps from commercially