The first carborane triflates: synthesis and reactivity of 1-trifluoromethanesulfonylmethyl- and 1,2-bis(trifluoromethanesulfonylmethyl)-o-carborane

Abstract

The first carborane triflates, namely, 1-trifluoromethanesulfonylmethyl-o-carborane (2) and 1,2-bis(trifluoromethanesulfonylmethyl)-o-carborane (7), were obtained in high yields in the reactions of 1-hydroxymethyl-o-carborane (1) or 1,2-bis(hydroxymethyl)-o-carborane (6) with triflic anhydride (Tf2O) in CH2Cl2 in the presence of pyridine. When an excess of pyridine is employed, 1-o-carboranylmethylpyridinium triflate (3), which retains a closo-icosahedral structure, or a pyridinium salt (4) with a zwitterionic nido-dicarbaundecaborate anion are obtained from 1, while the nido compound 8 is formed from 6. The reaction of compound 2 or 7 with excess pyridine also gave 3 or 8, respectively. Compound 2 proved to be a convenient carboranylmethylating agent which reacts with nucleophiles (e.g., potassium phthalimide, PPh3 or KCN) to give the corresponding substitution products N-[(o-carboranyl-1-yl)methyl]phthalimide (9), o-carboranylmethylphosphonium salt 10, and 1-cyanomethyl-o-carborane (11). All compounds were characterized by 1H and 11B NMR spectroscopy. The structures of compounds 4, 7 and 8 were established by X-ray analysis.

Influence of the CaCO3 nanoparticles on the molecular orientation of the polypropylene matrix

“…Using the alcohol 2 a as a model, we first tried to convert it into its corresponding sulfonate (Scheme ). Although the preparation of a mesylate from a primary carboranylmethyl alcohol has been described previously,13 we obtained a very poor conversion of our secondary alcohol 2 a , even under harsh reaction conditions (2 equiv of MsCl in refluxing CH 2 Cl 2 ). These disappointing results may be explained by the weak nucleophilicity of the hydroxyl function in 2 a , which is probably induced by the presence of two electron‐withdrawing substituents (phenyl and o ‐substituted carboranyl groups) and the bulkiness of the cluster.…”

Asymmetric hydrogenation with the use of chiral carborane amidophosphite derivatives in supercritical carbon dioxide and CH2Cl2

“…Hydrogena tion of chlorine containing enamide 7c with the use of ligand L 1 gave analogous results. For instance, applica tion of scCO 2 provides higher enantioselectivity as com pared to CH 2 Cl 2 (see Table 1, entries [13][14][15][16]. Hydroge nation of 7c using the catalytic system based on ami dophosphite L 2 in scCO 2 showed that higher pressure of H 2 assists in the increase in conversion (entries 17-18).…”

General Access to Aminobenzyl‐o‐carboranes as a New Class of Carborane Derivatives: Entry to Enantiopure Carborane–Amine Combinations

“…Using the alcohol 2 a as a model, we first tried to convert it into its corresponding sulfonate (Scheme 4). Although the preparation of a mesylate from a primary carboranylmethyl alcohol has been described previously, [13] we obtained a very poor conversion of our secondary alcohol 2 a, even under harsh reaction conditions (2 equiv of MsCl in refluxing CH 2 Cl 2 ). These disappointing results may be explained by the weak nucleophilicity of the hydroxyl function in 2 a, which is probably induced by the presence of two electron-withdrawing substituents (phenyl and o-substituted carboranyl groups) and the bulkiness of the cluster.…”

“…IR spectra were recorded on a Perkin-Elmer 1720X spectrometer. 1 H, 13 C, and 11 B NMR spectra were recorded at 300, 75, and 96 MHz, respectively, on a Bruker Advance-300 spectrometer and were referenced to the residual solvent [a] CÀH bond lengths are normalised to neutron distances; see interactions a) to f) in Figure 3, Figure 4. Symmetry codes: (a to f) = x, y, z.…”