Center for Magnetic Resonance

A.A. Melekhova, A.S. Novikov, K.V. Luzyanin, N.A. Bokach, G.L. Starova, V.V. Gurzhiy, V.Yu. Kukushkin

“Tris-isocyanide copper(I) complexes: Synthetic, structural, and theoretical study”

Inorg. Chim. Acta, 2015, 434, 31-36
DOI:10.1016/j.ica.2015.05.002

The reaction of CuBr with 3 equiv of CNR in CHCl₃ at RT furnished the pure tris-isocyanide complexes [CuBr(CNR)₃] [R = 2,6-Me₂C₆H₃ (Xyl) (1), 2-Cl-6-MeC₆H₃ (2), 2-Naphthyl (3), C₆H₁₁ (Cy) (4)] in 85–99% isolated yield. Compounds 1–4 were characterized by elemental analyses (C, H, N), high resolution ESI+-MS, IR, ¹H and ¹³C{1H} NMR spectroscopic techniques, and by single-crystal X-ray diffraction for 1 and 2. Coordination polyhedra of these two complexes are intermediate between tetrahedral and trigonal pyramidal with three isocyanide and one bromide ligands; the fragment M–C–N is bent [171.2(2)–175.6(2)°]. The influence of crystal packing effects on the geometric parameters of 1 as well as nature of the coordination Cu–C bonds and bond order of the formal triple C (triple bond)N bonds in this compound were also studied theoretically at the DFT level of theory. The crystal packing effects noticeably affect the values of the Cu–C–N angles and lead to a decrease of these angles approximately 10° relative to the gas phase geometries. Results of the AIM, NBO, and CDA analyses reveal that the Cu–C coordination bonds are of the electrostatic nature. Electrostatic interaction, unlike the covalent one, has no orientation, and it is the reason of the curved shape of the metal–ligand fragment.

D.I. Nilov, A.V. Vasilyev

“One-pot tandem hydrophenylation and ionic hydrogenation of 3-phenylpropynoic acid derivatives under superelectrophilic activation”

Tetrahedron Lett., 2015, 56, 5714-5717

DOI:10.1016/j.tetlet.2015.09.026

The reactions of esters and amides of 3-phenylpropynoic acid with strong Lewis acids AlX3 (X = Cl, Br) or conjugate Brønsted–Lewis superacids HX-AlX3 (X = Cl, Br) in benzene and cyclohexane at room temperature afforded 3,3-diphenylpropanoic acid derivatives in up to 94% yield. This tandem reaction of the acetylene bond proceeded by hydrophenylation followed by ionic hydrogenation.

A.N. Kazakova, R.O. Iakovenko, I.A. Boyarskaya, V.G. Nenajdenko, A.V. Vasilyev

“Acid-Promoted Reaction of Trifluoromethylated Allyl Alcohols with Arenes. Stereoselective Synthesis of CF3‑Alkenes and CF3‑Indanes”

J Org. Chem., 2015, 80, 9506-9517
DOI:10.1021/acs.joc.5b01398

Reaction of 4-aryl-1,1,1-trifluorobut-3-en-2-ols [CF₃-allyl alcohols, ArCH═CHCH(OH)CF₃] with arenes under activation with anhydrous FeCl3 or FSO3H was studied. We found that the transformation led to trifluoromethylated alkenes [Ar(Ar′)CHCH═CHCF₃] or 1-trifluoromethylated indanes (CF₃-indanes). The formation of these two types of reaction products strongly depends on the nucleophilicity of the starting arene and the electrophilicity of cationic intermediates generated from CF₃-allyl alcohols under reaction conditions. Benzene, anisole, veratrole, and ortho-xylene lead exclusively to CF₃-alkenes with an E-configuration. More π-donating polymethylated arenes (pseudocumene, mesitylene) afford only CF₃-indanes with a predominantly cis-orientation of substituents at positions 1 and 3 of the indane ring. Meta- and para-xylenes show an intermediate behavior; they may form both CF₃-alkenes and/or CF₃-indanes. The mechanisms of the investigated transformations are discussed.