38537-90-5

Upstream product

• 94-41-7 benzalacetophenone 
• 1052692-43-9 2,3-diphenyl-1,4-diiodo-1,3-diene 
• 100-47-0 benzonitrile 
• 614-47-1 1,3-diphenyl-propen-3-one 
• 4215-80-9 1,1,1-triphenylsilylamine 
• 98-81-7 1-bromovinylbenzene 
• 2548-47-2 2,3-diphenyl-1,3-butadiene 
• 502187-52-2 2-bromo-3,4,6-triphenyl-pyridine 

Relevant academic research and scientific papers

N-Silylenamines as Reactive Intermediates: Hydroamination for the Modular Synthesis of Selectively Substituted Pyridines

A modular and selective synthesis of mono-, di-, tri-, tetra-, and pentasubstituted pyridines is reported. Hydroamination of alkynes with N-silylamine using a bis(amidate)bis(amido)titanium(IV) precatalyst furnishes the regioselective formation of N-silylenamines. Addition of α,β-unsaturated carbonyls to the crude mixtures followed by oxidation affords 47 examples of pyridines in yields of up to 96%. This synthetic route allows for the synthesis of diverse pyridines containing variable substitution patterns, including pharmaceutically relevant 2,4,5-trisubstituted pyridines, using this one-pot protocol.

Nickel-catalyzed dehydrogenative [4 + 2] cycloaddition of 1,3-dienes with nitriles

Pyridines, which comprise one of the most important classes of the six-membered heterocyclic compounds, are widely distributed in nature, and the transition-metal-catalyzed [2 + 2 + 2] cycloaddition reaction of two alkynes and a nitrile is one of the most powerful methods for preparing versatile, highly substituted pyridine derivatives. However, the lack of chemo- and regioselectivity is still a crucial issue associated with fully intermolecular [2 + 2 + 2] cycloaddition. The present study developed the Ni(0)-catalyzed intermolecular dehydrogenative [4 + 2] cycloaddition reaction of 1,3-butadienes with nitriles to give a variety of pyridines regioselectively.

Diverse reactions of 1,4-dilithio-1,3-dienes with nitrites: Facile access to tricyclic Δ1-bipyrrolines, multiply substituted pyridines, siloles, and (Z,Z)-dienylsilanes by tuning of substituents on the butadienyl skeleton

Addition cyclization of 1,2,3,4-tetrasubstituted 1,4-dilithio-1,3-dienes (Type I) with four equivalents of various aromatic nitriles in the presence of hexamethylphosphoramide (HMPA) gives exclusively fully substituted pyridines in moderate to good yields. Similarly, trisubstituted pyridines can be prepared by the reaction of 2,3-dialkyl- or diaryl-substituted 1,4dilithio-1,3-dienes (Type II) with nitriles. However, five- or six-memberedring fused 2,3-disubstituted 1,4-dilithio1,3-dienes (Type III) reacted with various aromatic and aliphatic nitriles without a-hydrogen atoms to afford tricyclic Δ1- bipyrrolines in high yields. The reaction of six-membered-ring fused 2,3-disubstituted 1,4-dilithio-1,3-diene (Type III) with 2-cyanopyridine afforded the corresponding pyridine, and no tricyclic Δ1- bipyrroline was observed. Seven-membered-ring fused dilithiodienes reacted with PhCN or trimethylacetonitrile to afford the corresponding pyridines in good yield. When 1,2,3,4-tetrasubstituted dilithio reagents (Type I) were treated with Me3SiCN, a tandem silylation/intramolecular substitution process readily occurred to yield siloles, whereas the reaction of 2,3-disubstituted dilithio reagents (Types II and III) with Me3SiCN gave rise to (Z,Z)-dienylsilanes with high stereoselectivity. These results revealed that the formation of tricyclic Δ1-bipyrrolines, pyridines, siloles, and (Z,Z)-dienylsilanes are strongly dependent on the substitution patterns of the dilithio butadienes and the nature of the nitriles employed.

A New and Safe Approach to (N-Vinylimino)phosphoranes

1-benzotriazoles, obtained by Staudinger phosphenimide-forming reaction of (azidoalkyl)benzotriazoles, possessing a proton in a β-position to nitrogen reacted with sodium hydride in THF to afford (N-vinylimino)phosphoranes in high yields.The latter were trapped with chalcone to give the corresponding 2,4-diphenylpyridines.