A variety of polyhydro-6-aryl- and heteroarylcycloalka[b][1,5] naphthyridines have been efficiently prepared by thermally induced ring contraction of pyrido[2,3-b][1,5]thiazepines obtained by reacting lithiated 2-chloro-N-cycloalkylidene-3-pyridinimines with suitable O-ethyl thiocarboxylates.
Synthesis of Imidazo[4,5-<i>b</i>]pyridines and Imidazo[4,5-<i>b</i>]pyrazines by Palladium Catalyzed Amidation of 2-Chloro-3-amino-heterocycles
作者:Adam J. Rosenberg、Jinbo Zhao、Daniel A. Clark
DOI:10.1021/ol300359s
日期:2012.4.6
A facile synthesis of imidazo[4,5-b]pyridines and -pyrazines is described using a Pd-catalyzed amide coupling reaction. This reaction provides quick access to products with substitution at N1 and C2. A model system relevant to the natural product pentosidine has been demonstrated, as well as the total synthesis of the mutagen 1-Me-5-PhIP.
使用Pd催化的酰胺偶联反应描述了咪唑并[4,5- b ]吡啶和-吡嗪的简便合成方法。通过该反应,可以快速获得在N1和C2处被取代的产物。已经证明了与天然产物戊糖苷有关的模型系统,以及诱变剂1-Me-5-PhIP的全合成。
INFLUENCE DE LA NATURE DES SUBSTITUANTS DANS LES REACTIONS D'EXTRUSION DE SOUFRE LORS DE L'ELABORATION DE LA CHARPENTE PYRIDO[2,3-<i>b</i>[1,4]THIAZEPINE
A strategy involving the reaction between an azaallylic anion linked to a chloropyridine and different O-ethyl thiocarboxylates has shown to be effective for the synthesis of 2-aryl and 2-heteroarylpyrido[2,3-b][1,4]thiazepine However the presence of a saturated cycle fused with the thiazepine ring results in distorsion of the parent molecule, thus weakening the conjugation, and consequently induces the sulfur extrusion from the preliminary formed cycloadduct giving rise finally to 1,5-naphthyridines.
An Unusual Radical Smiles Rearrangement
作者:Eric Bacqué、Myriem El Qacemi、Samir Z. Zard
DOI:10.1021/ol051568l
日期:2005.8.1
Radicals derived from N-(alpha-xanthyl)acetanilides or N-(alpha-xanthyl)acetylaminopyridines possessing a substituent next to the nitrogen undergo a hitherto undocumented Smiles rearrangement proceeding through a four-membered ring. It was also found that under certain conditions the amidyl radical produced by cleavage of the four-membered ring intermediate can undergo fragmentation to give an isocyanate. Such fragmentations are unprecedented at temperatures corresponding to refluxing benzene or chlorobenzene.
Rapid and Efficient Microwave-Assisted Synthesis of 4-, 5-, 6- and 7-Azaindoles
作者:Nicolas Lachance、Myriam April、Marc-André Joly
DOI:10.1055/s-2005-872100
日期:——
imines/ enamines formed between aminopyridines and ketones are converted in moderate to good yields to the corresponding 4-, 5-, 6- or 7-azaindoles via the Hegedus-Mori-Heck reaction (intramolecular Heck reaction). A systematic examination of all isomeric azaindoles synthesis revealed this one-pot procedure to be general in scope.