RESUMO
[reaction: see text] Palladium-catalyzed cross-coupling of vinyl- and arylstannanes with pi-electron-deficient heteroaromatics was performed in good yields. This Stille-type reaction was carried out with a methylthioether function as an electrophile in the presence of a copper(I) bromide-dimethyl sulfide complex.
RESUMO
[reaction: see text] The first examples of C(6)-substituted 7-hydroxy-6,7-dihydro-5H-imidazo[1,2-b][1,2,4]triazines have been prepared by ring closure of different 5(2H)-1,2,4-triazin-3-ones 1a-c with 40% aqueous glyoxal and various nucleophiles (alcohols, thiols, or amines). The structure and exact stereochemistry of 2a was established by a single X-ray diffraction study and (1)H and (13)C NMR spectra analysis. The process was shown to be totally regio- and diastereoselective. A mechanism involving an imine intermediate was proposed.
RESUMO
In this paper, N-arylations between two heteroaryl compounds were studied. Conditions were found to generate selectively either 3- or 5-heteroarylamino-1,2,4-triazines by investigating anionic processes (use of bases such as 2,2',6,6'-tetramethylpiperidine/tBuOK/nBuLi) or Pd-catalyzed N-arylations [Pd(OAc)(2), xantphos]. These methods were successfully applied to a wide variety of heteroarylamines and allowed us to pursue our work on fused polynitrogen compounds synthesis.