Center for Magnetic Resonance

D.V. Kurandina, E.V. Eliseenkov, T.S. Khaibulova, A.A. Petrov, V.P. Boyarskiy

“Copper-catalyzed C-N bond cross-coupling of aryl halides and amines in water in the presence of ligand derived oxalyl dihydrazide: scope and limitation”

Tetrahedron, 2015, 71, 7931-7937
DOI:10.1016/j.tet.2015.07.071

An efficient and convenient method has been developed for the copper-catalyzed C–N bond cross-coupling of aryl bromides with electron-donor substituents and aliphatic amines in water. The new ligand system N-phenyloxalyl bishydrazide/hexane-2,5-dione has been shown to be considerably more efficient in the copper-catalyzed C–N bond cross-coupling reaction as compared to the ligands described in the literature and allowed decreasing of the catalyst amount (up to 2 mol %) to achieve acceptable yields of isolated products (46–84%). Acceptor substituted aryl bromides, aryl bromides with substituents in the ortho-position, and some aryl dichlorides can undergo the C–N cross-coupling under the developed conditions, but their reactivity is lower.

Yu.B. Koptelov, D.O. Antuganov, A.P. Molchanov, R.R. Kostikov

“Steric Hindrances to the Cycloaddition of (Z)-1-Arylmethylidene-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ides to N-Arylmaleimides”

Russ. J. Org. Chem., 2015, 7, 972-981
DOI:10.1134/S1070428015070143

Sterically hindered cycloaddition of (Z)-1-arylmethylidene-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ides to 4-mono- and 2,6-disubstituted N-arylmaleimides requires prolonged heating (40–60 h) at ~150–155°C and yields mixtures of diastereoisomeric cycloadducts. The observed diastereoselectivity is determined by both electronic and steric interactions, depending on the nature and position of substituents in the azomethine imine and maleimide. The reactions of (Z)-1-(2,6-dichlorobenzylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ide with 4-substituted N-arylmaleimides give mainly the corresponding cis adducts as a result of preferential exo attack by the dipolarophile, whereas trans adducts predominate in the cycloaddition of (Z)-1-(4-X-benzylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ide and (Z)-1-(2,6-dichlorobenzylidene) -5,5-dimethyl-3-oxopyrazolidin- 1-ium-2-ide to 2,6-disubstituted N-arylmaleimides.

S.A. Timofeeva, M.A. Kinzhalov, V.P. Boyarskiy, T.M. Buslaeva, E.A. Valishina, M. Haukka, K.V. Luzyanin, V.Yu. Kukushkin

“Application of palladium complexes bearing acyclic amino(hydrazido)carbene ligands as catalysts for copper-free Sonogashira cross-coupling”

J. Catalysis, 2015, 329, 449-456
DOI:10.1016/j.jcat.2015.06.001

Metal-mediated coupling of one isocyanide in cis-[PdCl₂(CNR¹)₂] (R¹ = C₆H₁₁ (Cy) 1, tBu 2, 2,6-Me₂C₆H₃ (Xyl) 3, 2-Cl-6-MeC₆H₃4) and various carbohydrazides R²CONHNH₂ [R² = Ph 5, 4-ClC₆H₄6, 3-NO₂C₆H₄7, 4-NO₂C₆H₄8, 4-CH₃C₆H₄9, 3,4-(MeO)₂C₆H₃10, naphth-1-yl 11, fur-2-yl 12, 4-NO₂C₆H₄CH₂13, Cy 14, 1-(4-fluorophenyl)-5-oxopyrrolidine-3-yl 15, (pyrrolidin-1-yl)C(O) 16, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propane-1-yl 17, EtNHC(O) 18] or sulfohydrazides R3SO2NHNH2 [R³ = Ph 19, 4-MeC₆H₄20] led to a series of (hydrazido)(amino)carbene complexes cis-[PdCl₂{C(NHNHX)double bond; length as m-dashN(H)R¹}(CNR¹)]; X = COR², SO₂R³ (21–48, isolated yields 60–96%). All prepared species were characterized by elemental analyses (C, H, N), HR ESI+-MS, IR, ¹H and ¹³C{¹H} NMR spectroscopy, and by a single-crystal X-ray diffraction for 38. Complexes 21–48 demonstrated excellent activity as catalysts in copper-free Sonogashira coupling of aryl iodides and a variety of aromatic terminal alkynes. Catalytic system runs in environmentally benign EtOH ensuring product yields of up to 75–96% and TONs of up to 104. Mechanism of the copper-free Sonogashira catalytic cycle involving 21–48 as catalysts was proposed upon identification of key intermediates using HRESI-mass.

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.

A.S. Pankova, M.V. Sorokina, М.А. Кuznetsov.

“Thermal rearrangement of 2,3-diaryl-1-phthalimidoaziridines”

Tetrahedron Lett., 2015, 56,5381-5385
DOI:10.1016/j.tetlet.2015.07.093

2,3-Diaryl-1-phthalimidoaziridines and 2,3-diaryl-1-phthalimidoaziridine-2-carbonitriles were found to readily undergo thermal rearrangement into imines via 1,2-migration of the phthalimido group and accompanying C–C bond cleavage. Isomerization proceeds regioselectively with preferable migration to the electron-deficient carbon atom. Interestingly, this reaction was found to predominate even in the presence of dipolarophiles.