69982-02-1Relevant articles and documents
A Strategy to Aminate Pyridines, Diazines, and Pharmaceuticals via Heterocyclic Phosphonium Salts
Patel, Chirag,Mohnike, Margaret,Hilton, Michael C.,McNally, Andrew
, p. 2607 - 2610 (2018)
A straightforward process to aminate pyridines and diazines is presented by reacting phosphonium salt derivatives with sodium azide. The iminophosphorane products are versatile precursors to several nitrogen-containing functional groups, and the process can be applied to building block heterocycles, to drug-like fragments, and for late-stage functionalization of complex pharmaceuticals. Appealing features of this strategy include using C-H bonds as precursors, precise regioselectivity, and a distinct scope from other amination methods, particularly those relying on halogenated azaarenes.
Thermolysis of benzannulated enyne-carbodiimides. Application in the synthesis of pyrido[1′,2′:1,2]pyrimido[4,5-b]indoles and related heteroaromatic compounds
Lu, Xiaoling,Petersen, Jeffrey L.,Wang, Kung K.
, p. 7797 - 7801 (2007/10/03)
Several derivatives of the pyrido[1′,2′:1,2]pyrimido[4,5-b]indoles 4 and the pyrazino[1′,2′:1,2]-pyrimido[4,5-b]indoles 14 were synthesized by treatment of the benzannulated enyne-isocyanates 8 with the iminophosphoranes 9 and 13, respectively, for the aza-Wittig reaction followed by thermolysis. The reaction presumably proceeds through an initial formation of the corresponding benzannulated enyne-carbodiimides, such as 10, followed by a formal intramolecular hetero Diels-Alder reaction. Surprisingly, when the iminophosphorane 17 was used for condensation with 8, the expected pyrimido[1′,6′:1,2]pyrimido[4,5-b]indoles 16 were not obtained. Instead, the isomeric pyrimido[6′,1′:2,3]pyrimido[4,5-b]indoles 21 were isolated. Presumably, an alternative reaction pathway involving an initial [2 + 2] cycloaddition reaction to form 19 followed by ring opening could lead to 20 and, after an intramolecular radical-radical coupling, 21. Treatment of the urea derivatives 24 with dibromotriphenylphosphorane also produced in situ the benzannulated enynecarbodiimides 25, which on thermolysis gave the isoquinolino[2′,1′:1,2]pyrimido[4,5-b]indoles 26. Methylation of 4a, 14a, and 26a with methyl iodide occurred exclusively at the site of the indolo nitrogen. The planar geometry of those novel heteroaromatic compounds, resembling many DNA-binding agents, makes them potential candidates as DNA intercalators.
Dihalogentriphenylphosphoranes in the synthesis of heterocycles, 29. A simple synthesis of pteridin-4-ones, from methyl-3-amino-2-pyrazinecarboxylate and pyrazino[3,1]oxazin-4-ones
Wamhoff,Kroth
, p. 405 - 410 (2007/10/02)
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.
