Efficient two-step access to azafluorenones and related compounds
摘要:
Crystals of a lithiocuprate prepared from copper(I) chloride and lithium 2,2,6,6-tetramethylpiperidide (2 equiv) were isolated and analyzed by X-ray diffraction as (TMP)(2)Cu(Cl)Li-2 center dot THF. The observation of this species is consistent with its having a role in deprotocupration-aroylation. Phenyl pyridyl ketones, phenyl quinolyl ketones, and phenyl thienyl ketones were prepared in tetrahydrofuran using the lithiocuprate and aroyl chorides as electrophiles. Diaryl ketones bearing a chloro group at the 2 position (of a pyridyl or phenyl group) thus synthesized were next converted through palladium-catalyzed ring closure to polycycles of the 5H-indeno[1,2-b]pyridin-5-one, 11H-indeno[1,2-b]quinolin-11-one, 9H-indeno[2,1-c]pyridin-9-one, and 8H-indeno[2,1-b]thiophen-8-one families. (C) 2013 Elsevier Ltd. All rights reserved.
Synthesis of azafluorenones and related compounds using deprotocupration–aroylation followed by intramolecular direct arylation
作者:Nada Marquise、Philip J. Harford、Floris Chevallier、Thierry Roisnel、Vincent Dorcet、Anne-Laure Gagez、Sophie Sablé、Laurent Picot、Valérie Thiéry、Andrew E.H. Wheatley、Philippe C. Gros、Florence Mongin
DOI:10.1016/j.tet.2013.09.030
日期:2013.11
The efficiency of the deprotocupration-aroylation of 2-chloropyridine using lithiocuprates prepared from CuX (X=Cl, Br) and LiTMP (TMP=2,2,6,6-tetramethylpiperidido, 2 equiv) was investigated. CuCl was identified as a more suitable copper source than CuBr for this purpose. Different diaryl ketones bearing a halogen at the 2 position of one of the aryl groups were synthesized in this way from azines and thiophenes. These were then involved in palladium-catalyzed ring closure: substrates underwent expected CH-activation-type arylation to afford fluorenone-type compounds, and were also subjected to cyclization reactions leading to xanthones, notably in the presence of oxygen-containing substituents or reagents. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
COMPOUNDS AND METHODS FOR HEMATOPOIETIC REGENERATION