21966-05-2

Upstream product

• 4463-42-7 benzyl boronic acid 
• 109-04-6 2-bromo-pyridine 
• 101-82-6 2-Benzylpyridine 
• 100-39-0 benzyl bromide 

Downstream Products

• 141368-81-2 1,3-Diphenyl-[1,3]azaphospholo[1,5-a]pyridine 

Relevant academic research and scientific papers

Synthesis of Enantioenriched 2-Alkyl Piperidine Derivatives through Asymmetric Reduction of Pyridinium Salts

An Ir-catalyzed enantioselective hydrogenation of 2-alkyl-pyridines has been developed using ligand MeO-BoQPhos. High levels of enantioselectivities up to 93:7 er were obtained. The resulting enantioenriched piperidines can be readily converted into biologically interesting molecules such as the fused tricyclic structures 5, 6, and 7 in 99:1 er, providing a novel, concise synthetic route to this family of chiral piperidine-containing compounds.

Asymmetric Hydrogenation of Pyridinium Salts with an Iridium Phosphole Catalyst

Iridium-catalyzed asymmetric hydrogenation of N-alkyl-2-alkylpyridinium salts provided 2-aryl-substituted piperidines with high levels of enantioselectivity. Simple benzyl and other alkyl groups successfully activated the challenging pyridine substrates toward hydrogenation. The use of the unusual chiral-phosphole-based MP2-SEGPHOS was the key to the success of this approach which provides a versatile and practical procedure for the synthesis of chiral piperidines. Ring to ring: Simple N-benzyl and N-alkyl groups successfully activated pyridine substrates toward hydrogenation. The use of the unusual chiral phosphole-based ligand L was the key to the success of this approach, which provides a versatile and practical procedure for the synthesis of chiral piperidines. cod=1,5-cyclooctadiene.

Efficient and chemoselective reduction of pyridines to tetrahydropyridines and piperidines via rhodium-catalyzed transfer hydrogenation

Promoted by iodide anion the rhodium complex dimer, [Cp RhCl 2]2, catalyzes efficiently the transfer hydrogenation of various quaternary pyridinium salts under mild conditions, affording not only piperidines but also 1,2,3,6-tetrahydropyridines in a highly chemoselective fashion, depending on the substitution pattern at the pyridinium ring. The reduction is conducted in azeotropic formic acid/triethylamine (HCOOH-Et 3N) mixture at 40 °C, with catalyst loadings as low as 0.005mol% being feasible. Copyright

The role of ion/neutral complexes in the fragmentation of N-benzyl-(alkylpyridinium) ions

N-Benzylpyridinium ions bearing an alkyl group at the pyridine nucleus were studied as potential precursors of gaseous ion/neutral complexes. The occurrence of I/N complexes [C6H5CH2 + ? alkylpyridine] was probed by the reactivity of the potential benzylic hydride donor sites present in the ortho-, meta- and para-alkyl groups (R = methyl, ethyl, isopropyl and benzyl). Collision-induced dissociation of the ions, carried out in an electrical ion cage mass spectrometer, revealed that hydride transfer strongly depends both on the energy requirements of the hydride transfer but also on the position of the hydride donor. Hydride transfer, giving rise to the loss of toluene, was found to occur exclusively with those N-benzylpyridinium ions which bear an isopropyl or a benzyl substituent in the ortho position of the pyridine ring, thus reflecting the intermediacy of I/N complexes. All of the putative hydride donor alkyl groups were found to be non-reactive in the meta and para positions, as were methyl and ethyl groups even in the ortho positions. Density functional calculations (B3LYP/6-311+G/3d,2p)//(B3LYP/6-31+G(d)) on the hydride-transfer and simple-cleavage channels were carried out to help rationalizing these observations. The results suggest that the intra-complex hydride abstraction from the 3- and 4-isopropyl- and from the 3- and 4-benzylpyridine neutrals, although being thermodynamically favorable, is suppressed by substantial intra-complex rotational (or reorientation) barriers.

Reaction of N-alkylpyredinium salts with phosphorus trichloride

1-Alkylpyridinium bromides 1 having activated N-methylene group react with phosphorus trichloride to give N-(dichlorophosphinomethylene)pyridinium ylides 2. The site of the reaction in 1,2-dialkylpyridinium halides 3 under these conditions is determined by the relative activation of 1- and 2-methylene groups; in the absence of sufficient activation of N-methylene group, reaction occurs at the 2-methylene group to give dichlorophosphinylated anhydrobases 5 and 11. 1,4-Dialkylpyridinium bromide 13 behaves analogously to give the corresponding dichlorophosphinylated anhydrobase 14.