Application of biphasic reaction procedure using ferric chloride dissolved in an imidazolium salt and benzotrifluoride (FeIm-BTF procedure) to aza-Prins cyclization reaction

Preparation of trans-2-Substituted-4-halopiperidines and cis-2-Substituted-4-halotetrahydropyrans via AlCl3-Catalyzed Prins Reaction

“…trans -4-Chloro-2-(3-methoxy­phenyl)-1-tosyl­piperidine (major diastereomer, white solid, mp = 106–108 °C): 1 H NMR (400 MHz, CDCl 3 ) δ = 7.69 (d, J = 8.1 Hz, 2H), 7.25 (d, J = 8.1 Hz, 2H), 7.19–7.11 (m, 1H), 6.81 (d, J = 7.7 Hz, 1H), 6.75–6.71 (m, 2H), 5.28 (d, J = 4.2 Hz, 1H), 3.91–3.77 (m, 2H), 3.67 (s, 3H), 3.01–2.91 (m, 1H), 2.67–2.57 (m, 1H), 2.37 (s, 3H), 1.87–1.76 (m, 2H), 1.50 (dd, J = 12.8, 4.8 Hz, 1H); 13 C NMR (100 MHz, CDCl 3 ) δ = 159.2, 142.6, 138.1, 136.9, 129.0, 128.9, 125.9, 117.6, 111.5, 111.5, 55.0, 54.2, 51.8, 40.4, 36.7, 34.2, 20.5. NMR data were in agreement with the reported results …”

“…The trans -selectivity for aza-Prins cyclization may be attributed to the steric repulsion between Ts and R groups. Because of this repulsion, the Lewis acid assisted formation of the E -sulfoniminium intermediate would be more favorable during the reaction. Aza-Prins cyclization proceeded via a six-membered ring transition state with the Ts group at the equatorial position and the R group at the axial position, and attack of the halide anion occurred from the equatorial direction, leading to trans -halopiperidine as the major product (Scheme , path a) …”

Fluorous Organic Hybrid Solvents for Non-Fluorous Organic Synthesis

“…Hasegawa and his coworkers also developed a binary solvent system comprised of BTF and ionic liquids for a similar oxidative ring-opening reaction of siloxycyclopropanes by FeCl 3 [10]. Aza-Prins cyclization reactions in a similar biphasic system (BTF and FeCl 3 -BminFeCl 4 ) gave piperidine derivatives in good yields (Scheme 2) [11].…”

Synthesis of mesoporous carbon/iron carbide hybrids with unusually high surface areas from the ionic liquid precursor [Bmim][FeCl4]

“…Ionic liquids (ILs) have gained attention as solvents, templates, dispersion media, and precursors for inorganic materials. [1][2][3][4][5][6][7][8][9][10] Iron-containing ILs have attracted interest for their catalytic activity, [11][12][13][14][15][16][17][18][19] as components in hybrid materials, 20 and for their physical behavior such as the thermally induced demixing from aqueous solution. 21 Iron carbide is interesting, among others, because of its high thermal stability.…”