Efficient synthesis of 2- and 3-substituted-2,3-dihydro [1,4]dioxino[2,3-b]pyridine derivatives

A versatile new approach for the synthesis in three steps of 2-substituted-2,3-dihydro[1,4]dioxino[2,3-b]pyridines B via a Smiles rearrangement using easily available reagents is described. A study illustrating the influence of experimental conditions on the progress of the reaction is reported.     

Lithiation directed by amino alkoxides. Application to the synthesis of new disubstituted dihydrodipyridopyrazines

The synthesis of new 4,6-disubstituted dihydrodipyridopyrazines starting from corresponding carboxaldehydes via lithiation directed by alpha-amino alkoxides is described. The N,N,N'-trimethylethylenediamine was used as amine component for in situ formation of the alpha-amino alkoxides. After optimization, this reaction allowed easy access to new interesting starting materials for further applications by palladium-catalyzed reactions.     

Functionalization of dihydrodipyridopyrazines involving palladium-catalyzed coupling reactions

Various 4-substituted dihydrodipyridopyrazines were synthesized by palladium-mediated cross-coupling reactions. Starting from the corresponding 4-iodo or 4-bromo derivatives, the incorporation of aryl, vinyl, alkynyl and methoxycarbonyl groups is described.     

Efficient and selective synthesis of alkoxy substituted di(pyridin-2-yl)amines and N-arylpyridin-2-ylamines

The formation of alkoxy substituted di(pyridin-2-yl)amines and N-arylpyridin-2-ylamines by nitro group reduction is described. Unexpected substitution of ortho with the amino at C-6 was observed during the reduction using SnCl₂·2H₂O in different alcohols. The influence of the nature of the atom at the 3- and 5-positions of nitro-substituted di(pyridin-2-yl)amines and N-arylpyridin-2-ylamines was investigated.