New Approach to the Practical Synthesis of Tri- or Tetrasubstituted Pyrimidine Derivatives: A Four-Component Coupling Reaction from a Functionalized Silane, Two Types of Aromatic Nitriles, and Acetals

Synthesis of Polysubstituted Pyrimidines through Palladium-Catalyzed Isocyanide Insertion to 2H-Azirines

The domino process of the palladium-catalyzed coupling reaction of isocyanides with 2H-azirine provides various tetrasubstituted pyrimidines via one C-C bond and two C-N bond formations with satisfactory yields. The title compounds are obtained with good functional group tolerance, high atom economy, and broad substrate scopes.

Synthesis of pyrimidines by direct condensation of amides and nitriles

A protocol for the single-step synthesis of pyrimidine derivatives by condensation of N-vinyl or N-aryl amides with nitriles is described. Gram-scale synthesis of 4-tert-butyl-2-phenyl-7,8-dihydro-6H-pyrano[3,2-d]pyrimidine serves as a representative procedure for this methodology for azaheterocycle synthesis. This chemistry involves amide activation with trifluoromethanesulfonic anhydride in the presence of 2-chloropyridine and the necessary nitrile. Nucleophilic addition of the nitrile to an activated intermediate followed by annulation affords the pyrimidine product in a single step. The total time necessary for the completion of this procedure is approximately 3 h. This chemistry has been applied to a wide range of amides and nitriles including optically active derivatives.

Novel synthesis of 7-fluoro-8-(trifluoromethyl)- 1H-1,6-naphthyridin-4-one derivatives: intermolecular cyclization of an N-silyl-1-azaallyl anion with perfluoroalkene and subsequent intramolecular skeletal transformation of the resulting pentasubstituted pyridines

In this study, fluorine-containing pentasubstituted pyridine derivatives 9a-m were prepared regioselectively in good yields by the intermolecular cyclization of a variety of N-silyl-1-azaallylic anion intermediates 7, which were generated from a functionalized silane 5 and an aromatic/aliphatic nitrile 6 with perfluoroalkene 8. Also, 7-fluoro-8-(trifluoromethyl)-1H-1,6-naphthyridin-4-one derivatives 11a-k were synthesized in excellent yields by the subsequent base-promoted intramolecular skeletal transformation of the resulting pyridine derivatives 10a-k.

Single-Step Synthesis of Pyrimidine Derivatives

We describe a single-step conversion of various N-vinyl and N-aryl amides to the corresponding pyrimidine and quinazoline derivatives, respectively. The process involves amide activation with 2-chloropyridine and trifluoromethanesulfonic anhydride followed by nitrile addition into the reactive intermediate and cycloisomerization. In situ nitrile generation from primary amides allows for their use as nitrile surrogates. The use of this chemistry with sensitive N-vinyl amides and epimerizable substrates in addition to a wide range of functional groups is noteworthy.