Syntheses and Reactivities of Disubstituted and Trisubstituted Fluorous Pyridines with High Fluorous Phase Affinities:  Solid State, Liquid Crystal, and Ionic Liquid-Phase Properties

Abstract

Reactions of 2,6-dibromo-, 3,5-dibromo-, and 2,4,6-tribromopyridine with IZnCH(2)CH(2)R(f8) (R(f8) = (CF(2))(7)CF(3)) in THF at 65 degrees C in the presence of trans-Cl(2)Pd(PPh(3))(2) (5 mol %) gave the fluorous pyridines 2,6- and 3,5-NC(5)H(3)(CH(2)CH(2)R(f8))(2) (1 and 2; 85%, 31%) and 2,4,6-NC(5)H(2)(CH(2)CH(2)R(f8))(3) (3, 61%). Reaction of 2,6-pyridinedicarboxaldehyde with [Ph(3)PCH(2)CH(2)R(f8)](+)I(-)/K(2)CO(3) (p-dioxane/H(2)O, 95 degrees C) gave 2,6-NC(5)H(3)(CH[double bond]CHCH(2)R(f8))(2) (95%; 70:30 ZZ/ZE), which was treated with H(2) (1 atm, 12 h) and 10% Pd/C to yield 2,6-NC(5)H(3)(CH(2)CH(2)CH(2)R(f8))(2) (5, 95%), a higher homologue of 1. Longer reaction times afforded piperidine cis-2,6-HNC(5)H(8)(CH(2)CH(2)CH(2)R(f8))(2) (6, 98%). The stereochemistry was established by NMR analysis of the N-benzylpiperidine. Pyridines 1-3 and 5 are low-melting white solids with CF(3)C(6)F(11)/toluene partition coefficients (24 degrees C) of 93.8:6.2, 93.9:6.1, >99.7:<0.3, and 90.4:9.6, respectively (6, 93.6:6.4). Reaction of 1 and CF(3)SO(3)H gave a pyridinium salt, and Cl(2)Pd(NCCH(3))(2) (0.5 equiv) yielded trans-Cl(2)Pd(1)(2). The crystal structure of the former, which also exhibited liquid crystalline and ionic liquid phases, was determined.

Thermoregulated Liquid/Liquid Catalyst Separation and Recycling

“…The original aim was to modify known ligands with fluorous alkyl groups ("pony tails") to effect their immiscibility with organic solvents at low temperatures. In this regard triarylphosphines, [18] triaryl phosphites, [19] pyridines, [20] pincer ligands [21] and even chiral phosphines were modified by introduction of several fluorous alkyl groups [22] ( Figure 2) and the synthesis was optimised. [23] The total affinity of these ligands to a fluorous phase depends on the number and length of the "pony tails" and is therefore adjustable.…”

A New and Flexible Synthesis of 4‐Hydroxypyridines: Rapid Access to Caerulomycins A, E and Functionalized Terpyridines

“…The convenient preparation of fluorous [11] pyridine derivatives 6 b and 7 b bearing a CF 3 A C H T U N G T R E N N U N G (CF 2 ) 6 group at C-2 position in high yield (entry 2) further highlights the synthetic potential of this methodology. Notably pyridine derivatives 7 b, 7 d and 7 g can serve as promising building blocks for novel fluorinated functional materials.…”

High Sensitivity Method for Determination of Trace Curcumin in the Aqueous Phase

“…, electrochemistry [27][28][29] , and extraction of organic pollutants 22,[30][31][32] . To the best of our knowledge, the use of TAIL-DLPME combined with spectrophotometry at 3500 rpm (1684×g).…”