Dihalogentriphenylphosphorane in der Heterocyclensynthese, 29.<sup>1</sup>Eine einfache Synthese von Pteridin-4-onen aus 3-Amino-2-pyrazincarbonsäuremethylester und Pyrazino[3,1]oxazin-4-onen
作者:Heinrich Wamhoff、Elmar Kroth
DOI:10.1055/s-1994-25487
日期:——
Dihalogentriphenylphosphoranes in the Synthesis of Heterocycles, 29.1 A Simple Synthesis of Pteridin-4-ones, from Methyl 3-Amino-2-pyrazinecarboxylate and Pyrazino[3,1]oxazin-4-ones Methyl 3-amino-2-pyrazinecarboxylate(3) affords the synthetically useful 3-aroylaminopyrazin-2-carboxylates 5a-f with aroyl chlorides, which are converted with dibromotriphenylphosphorane into 2-arylpyrazino[2,3-d][3,1]oxazin-4-ones 6a-f. Nucleophilic attack at the carbonyl function of these oxazinones results in ring cleaved amides which can be recyclized with dibromotriphenylphosphorane to afford 2-arylpteridin-4-ones 7a-f.
unexpectedly, in stead of pyrido[2,3-d]pyrimidine derivatives, by the intermolecular aza-Wittig reaction of methyl 2-(N-triphenylphosphoranylidene)aminonicotinate 3 with aryl isocyanates followed by attempted heterocyclization by use of prim-amines. A novel sequential aza-Wittig / cycloaddition / ring-transformation mechanism for the formation of 10 has been reported based on the isolation and characterization
通过分子间的氮杂-Wittig反应,意外地获得了(2-氧-1,2-二氢吡啶-3-基)-1,3,5-三嗪衍生物10,而不是吡啶并[2,3- d ]嘧啶衍生物。 2-(N-三苯基正膦亚基)氨基烟酸甲酯3与芳基异氰酸酯的反应,然后尝试使用伯胺进行杂环化。一种新颖的顺序氮杂维蒂希/环加成/环变换机构,用于形成10已经报道基于所述隔离和关键中间体的表征,吡啶并[1,2一个] [1,3,5]三嗪15形成的通过 最初生产的碳二亚胺与异氰酸芳基酯的[4 + 2]环加成反应。
Reaction between triphenylphosphine and aromatic amines in the presence of diethyl azodicarboxylate: an efficient synthesis of aryliminophosphoranes under neutral and mild conditions
作者:Mehdi Adib、Ehsan Sheikhi、Azadeh Deljoush
DOI:10.1016/j.tet.2011.03.097
日期:2011.6
An efficient synthesis of aryliminophosphoranes is described. A mixture of an aromatic amine, diethylazodicarboxylate and triphenylphosphine undergo a Mitsonobu type reaction at ambient temperature in dry dichloromethane to afford aryliminophosphoranes in excellent yields.