Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• configuration of the products by modifying the substituents on the nitrogen of the pyridinium salts. Further, the method showed a wide substrate scope for both the Z- and E-alkenylated products in which Z-selectivity was achieved when N-methylpyridinium salts were used and E-selectivity when N-benzylpyridinium

• (II)–alkenyl intermediate 88. Then, the intermediate 88 undergoes protio-depalladation and demethylation to yield the Z-isomer 85 (Scheme 17b). In case of N-benzylpyridinium salts 83, first debenzylation occurs to form 2-pyridyl–Cu(I) species 89 in the presence of CuBr which then coordinates to the Pd

Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts

• David Schönbauer,
• Carlo Sambiagio,
• Timothy Noël and
• Michael Schnürch

Beilstein J. Org. Chem. 2020, 16, 809–817, doi:10.3762/bjoc.16.74

• demonstrate the deaminative coupling of N-benzylpyridinium Katritzky salts with THIQs under ruthenium photoredox catalysis. During the preparation of this article, a similar transformation was disclosed using an iridium photoredox catalyst [47]. Results and Discussion We started our investigations by

Synthesis of 3-aminocoumarin-N-benzylpyridinium conjugates with nanomolar inhibitory activity against acetylcholinesterase

• Nisachon Khunnawutmanotham,
• Cherdchai Laongthipparos,
• Patchreenart Saparpakorn,
• Nitirat Chimnoi and
• Supanna Techasakul

Beilstein J. Org. Chem. 2018, 14, 2545–2552, doi:10.3762/bjoc.14.231

• 10210, Thailand 10.3762/bjoc.14.231 Abstract A series of 3-amino-6,7-dimethoxycoumarins conjugated with the N-benzylpyridinium moiety through an amide-bond linkage was synthesized and evaluated for their acetylcholinesterase inhibitory activity. A number of the benzylpyridinium derivatives exhibited

• target enzyme by a dual binding site mechanism whereby the coumarin portion binds with the peripheral anionic site while the N-benzylpyridinium residue binds with the catalytic anionic site of the enzyme. Keywords: acetylcholinesterase inhibitor; 3-aminocoumarin; N-benzylpyridinium; dual binding site

• scopoletin portion of the compound binds to amino acid residues in PAS, whereas the N-benzylpyridinium moiety binds to those present in the CAS of AChE. To develop potent AChE inhibitors, we were interested in aminocoumarin as a replacement of scopoletin due to the presence of the amino group in the former

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• ). The latter was synthesized from the known 2-bromo-6-(bromomethyl)naphthalene (2) which was prepared in two steps according to published procedures [26] from commercially available methyl 6-bromo-2-naphthoate. The reaction of the (bromomethyl)naphthalene 2 with (1,3-dioxolan-2-yl)pyridine yielded the N

• -benzylpyridinium derivative 3 and the subsequent cyclodehydration [27] in refluxing HBr (w = 48%) gave the bromonaphtho[1,2-b]quinolizinium 4 in 57% overall yield (Scheme 1). The Suzuki–Miyaura coupling reactions of 3-bromonaphthoquinolizinium derivative 4 with the arylboronic acids 5a–e were performed under

The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts

• Kari Raatikainen,
• Massimo Cametti and
• Kari Rissanen

Beilstein J. Org. Chem. 2010, 6, No. 4, doi:10.3762/bjoc.6.4

• first focused our attention on N-benzylpyridinium salts, which should completely suppress the strong hydrogen bond interactions and give space to strong XB interaction instead if an iodine substituent would sit on the aromatic ring. Therefore, we prepared N-benzyl-3-iodopyridinium chloride (9) by

• and an ethanol solvent molecule (Figure 5a). The electron withdrawing effect of N-benzylpyridinium cation gives rise to short halogen bonds, where the R = 0.83 and R = 0.85 for I1···Cl1 and I15···Cl2, respectively (Table 4). The short halogen bond distances are consistent with the linearity of C–I1