340771-06-4

Upstream product

• 108-99-6 3-Methylpyridine 
• 59046-22-9 (3-methylpyridin-1-ium-1-yl)amide 
• 31382-86-2 N-<(phenylcarbonyl)imino>-3-methylpyridinium inner salt 
• 42599-24-6 E-styryl iodide 

Relevant academic research and scientific papers

Synthesis of 2- and 2,3-substituted Pyrazolo[1,5- a ]pyridines: Scope and mechanistic considerations of a domino direct alkynylation and cyclization of n -iminopyridinium ylides using alkenyl bromides, alkenyl iodides, and alkynes

Direct functionalization and tandem processes have both received considerable recent interest due to their cost and time efficiency. Herein we report the synthesis of difficult to obtain 2-substituted pyrazolo[1,5-a] pyridines through a tandem palladium-catalyzed/silver-mediated elimination/direct functionalization/cyclization reaction involving N-benzoyliminopyridinium ylides. As such, these biologically important molecules are prepared in an efficient, high-yielding manner, only requiring a two-step sequence from pyridine. Aryl-substituted alkenyl bromides and iodides are effective ylide coupling partners. Mechanistic studies led to the use of terminal alkynes, which extended the scope of the reaction to include alkyl substitution on the unsaturated reactive site. The optimization, scope, and mechanistic considerations of the process are discussed.

Synthesis of 2-Substituted Pyrazolo[1,5-a]pyridines through Cascade Direct Alkenylation/Cyclization Reactions

[Chemical equation presented] The synthesis of 2-substituted pyrazolo[1,5-a]pyridines from N-iminopyridinium ylides is described. These medicinally interesting compounds are formed through a cascade process involving a palladium-catalyzed direct alkenylation reaction followed by silver-mediated cyclization. The reaction can be performed with a wide range of electron-poor and electron-rich alkenyl iodides in good yields. This work represents perhaps the most direct route for the preparation of these compounds.