Organoselenium‐Catalyzed Regioselective C−H Pyridination of 1,3‐Dienes and Alkenes

Abstract

An efficient approach for organoselenium-catalyzed regioselective C-H pyridination of 1,3-dienes to form pyridinium salts has been developed. This method was also successfully applied to direct C-H pyridination of alkenes. Fluoropyridinium reagents, or initially loaded pyridine derivatives, acted as pyridine sources in the pyridination reactions. The obtained pyridinium salts could be further converted under different conditions. This work is the first example of catalytic C-2 direct C-H functionalization of 1,3-dienes and the first case of organoselenium-catalyzed C-H pyridination.

Seleno‐Michael Reaction of Stable Functionalised Alkyl Selenols: A Versatile Tool for the Synthesis of Acyclic and Cyclic Unsymmetrical Alkyl and Vinyl Selenides

“…GC-MS was performed on a Varian CP 3800/Saturn 2200 instrument. 1 H and 13 13 C). Diphenyl diselenide (PhSe) 2 was used as an external reference for 77 Se NMR (δ = 461 ppm).…”

“…Chemical shifts (δ) are given in parts per million (ppm), and coupling constants (J) are given in Hertz (Hz), rounded to the nearest 0.1 Hz. 1 H NMR data are reported as follows: chemical shift, integration, multiplicity (s = singlet, d = doublet, t = triplet, ap d = apparent doublet, m = multiplet, dd = doublet of doublet, bs = broad singlet, bd = broad doublet, ecc. ), coupling constant (J) or line separation (ls), and assignment.…”

“…Organoselenium compounds occupy a relevant position in chemical sciences, with broad application in organic synthesis, [1] materials science [2] and polymer chemistry. [3] In addition, selenium-containing organic molecules play an increasingly important role in biology and in medicinal chemistry, [4] since they possess antioxidant, [5] enzyme modulator, [6] anticancer, [7] and cells growth inhibitor [8] activities.…”

Oxidative selenofunctionalization of allenes: convenient access to 2-(phenylselanyl)-but-2-enals and 4-oxo-3-(phenylselanyl)pent-2-enoates

“…3 As a result, several synthesis protocols toward organoselenium derivatives have been described starting from allenes. 4 Inspired by the recently described organoselenium-mediated C-H pyridination of 1,3-dienes using 1-fluoropyridinium reagents (Scheme 1a), 5 we decided to test the related C-H functionalization of 1,2-dienes. However, we did observe the selective formation of α-selenoenals and α-selenoenones (Scheme 1b), 6 probably via the controlled electrophilic addition of the selenium reagent to the allene moiety followed by adventitious water attack and concomitant oxidation.…”

Selenated and Sulfurated Analogues of Triacyl Glycerols: Selective Synthesis and Structural Characterization

“…Having developed ac onveniento ne pot silicon-mediated procedure to access 2-seleno-1-thioglycerol esters 3,w e soughtt oe valuatew hether the chemistry of silyl chalcogenides could also be exploited to discloseaselectivea ccess to selenides tetraesters 7,o btained as side products in the previ-ous reactions (Scheme 4). Selenides are indeedv aluable compounds for their application as key intermediates in organic synthesis [17] and, more recently, as antioxidants, [18] carbonic anhydrase inhibitors [19] and for their thiol peroxidase catalytic activity. [18] In this context,t he selective synthesis of functionalized selenides,b earing two fatty acid esters and two fatty acid thiolesters would be highly desirable in order to modulate the lipophilicity of these systems.…”