A general route to 1,2,4-trisubstituted pyrimidines is described in one to three steps from a common key precursor, diazadienium iodide 2. An efficient preliminary [4+2] cyclocondensation reaction between the azabutadiene building block 2 and various iso(thio)cyanates constitutes an original construction of the pyrimidine skeleton. Subsequent structural modifications on the heterocycle allow the elaboration
A facile and simple regioselective synthesis of uracils and their thio analogues has been achieved by cyclocondensation of a common precursor, diazadienium iodide 1, and isothiocyanates 2a,b. The key step in this synthetic process is the preparation of 4-methylsulfanylpyrimidine-2-thiones 3a,b, which after further elaboration gave the expected uracil analogues 4a,b-8a,b.
2-Aminothiabutadiene as Useful Building Block in the Synthesis of 2-Aminothiopyrans and 2-Aminothiophenes
作者:David Deniaud、Aélig Robin、Jean-Claude Meslin
DOI:10.1055/s-2004-829112
日期:——
We report a reliable and regiocontrolled alternative route to unsubstituted 2-aminothiopyrans and 2-aminothiophenes. These sulfur heterocycles were prepared by reaction of protected aminothiabutadiene 1 with acrylic dienophiles or acceptor-substituted halomethyl compounds. All compounds were fully characterized by IR, HRMS, and 13C and 1H NMR spectroscopy.
Synthesis of pyridone and pyridine rings by [4+2] hetero-cyclocondensation
作者:Aélig Robin、Karine Julienne、Jean Claude Meslin、David Deniaud
DOI:10.1016/j.tetlet.2004.10.142
日期:2004.12
Substituted pyridones and pyridines have been synthesised efficiently by employing iminium salt as a key precursor. These compounds were prepared using tandem [4+2] cycloaddition/deamination between azabutadiene and dienophiles.