Center for Magnetic Resonance

A.S. Bogachenkov, A.V. Dogadina, V.P. Boyarskiy, A.V. Vasilyev

“Acid-promoted transformations of 1-(diphenylphosphoryl)allenes: synthesis of novel 1,4-dihydrophosphinoline 1-oxides”

Org. Biomol. Chem., 2015, 13, 1333-1338

DOI: 10.1039/c4ob02269f

1-(Diphenylphosphoryl)alka-1,2-dienes (phosphonoallenes) in Brønsted (super)acids (TfOH, FSO3H, and H2SO4) at −70 to 120 °C for 30 min to 4 h gave, at first, (3-hydroxyalk-1-en-1-yl)diphenylphosphine oxides, as kinetically favorable reaction products, that are further converted into 1-phenyl-1,4-dihydrophosphinoline 1-oxides as thermodynamically stable compounds. The latter compounds are formed from phosphonoallenes under the action of a strong Lewis acid AlCl3 at room temperature for 10–120 min. This is a novel, simple and efficient (short reaction time, high yields) method for synthesis of such 1,4-dihydrophosphinoline 1-oxides.

M.S. Novikov, A.F. Khlebnikov, N.V. Rostovskii, S.Tcyrulnikov, A.A. Suhanova, K.V. Zavyalov, D.S. Yufit

“Pseudopericyclic 1,5- versus Pericyclic 1,4- and 1,6-Electrocyclization in Electron-Poor 4‑Aryl-2-azabuta-1,3-dienes: Indole Synthesis from 2H‑Azirines and Diazo Compounds”

J Org. Chem., 2015, 80, 18-29

DOI: 10.1021/jo501051n

Transformations of 2-azabuta-1,3-dienes, formed in Rh2(OAc)4-catalyzed reactions of diazo carbonyl compounds with 2H-azirines, dramatically depend on the nature of substituents. 4,4-Diphenyl-2-azabuta-1,3-dienes with two electron- acceptor substituents at C1 undergo thermal 1,5-cyclization to give indoles in good yields.
The increase in electronwithdrawing ability of C1-substituents facilitates the reaction that proceeds via pseudopericyclic 1,5-electrocyclization of 2- azabutadiene into 7aH-indolium ylide followed by prototropic shift. 3,4-Diphenyl-2-azabuta-1,3-dienes, resulting from reaction of 2,3-diphenyl-2H-azirine and diazo compounds, do not produce indoles via 1,5-cyclization due to the trans-configuration of the 4-Ph-group and the nitrogen, but undergo 1,4-cyclization to 2,3- dihydroazetes. 1,6-Cyclization into 2H-1,4-oxazines with participation of the oxygen of ester or amide group at C1 of corresponding 2-azabuta-1,3-dienes does not take place due to kinetic and thermodynamic reasons. Instead of this, 1,6-electrocyclization with participation of phenyl substituent at C4 of the 2-azabuta-1,3- dienes, providing isoquinoline derivatives, can occur at elevated temperatures. The DFT-calculations (mPWB1K/6-31+G(d,p)) confirm the dependence of 2-azabuta-1,3-diene transformation type on the nature of substituents.

A.S. Pankova, M.A. Samartsev, I.A. Shulgin, P.R. Golubev, М.А. Кuznetsov

“Synthesis of thiazolidines via regioselective addition of unsymmetric thioureas to maleic acid derivatives”

RSC Advances, 2014, 4, 51780-51786
DOI: 10.1039/c4ra07840c

Wide range of unsymmetric thioureas has been studied in reaction with N-arylmaleimides and maleic anhydride. The regioselectivity of the addition depends not only on steric factors but on both solvent polarity and type of maleic acid derivative (imide or anhydride). The general regularities have been established providing practical guidelines to control the reaction result. The unequivocal structural assignment of all products has been done using NMR spectroscopy including 15N–1H HMBC experiments.

T.M. Dau, Y.-A. Chen, A.J. Karttunen, E.V. Grachova, S.P. Tunik, K.-T. Lin, W.-Y. Hung, P.-T. Chou, T.A. Pakkanen, I.O. Koshevoy

“Tetragold(I) Complexes: Solution Isomerization and Tunable Solid-State Luminescence”

Inorg. Chem., 2014, accepted

DOI: 10.1021/ic501470v

In this study, a new family of tetranuclear gold(I)triphosphine derivatives bearing alkynyl and thiolate groups have been efficiently synthesized by treating the polymeric acetylides (AuC2R)n or a thiolate (AuSPh)n sequentially with the (a) phosphine ligand and (b) cationic complex [Au3(P^P^P)2]3+ (P^P^P = PPh2CH2PPhCH2PPh2). The clusters [Au4(P^P^P)2(C2R)2]2+ [R= Ph (1), biphenyl (2), terphenyl (3), C6H4OMe (4), C6H4NMe2 (5), C6H11O (6), and C6H4CF3 (7)] and [Au4(P^P^P)2(SPh)2]2+(8) were characterized by X-ray crystallography in the solid state.
NMR spectroscopic investigations in solution revealed that the majority of alkynyl clusters 1−7 exist as two isomeric species in slow chemical equilibria. All complexes 1−8 exhibit moderate-to-strong photoemission in the solid state with quantum yields from 0.07 to 0.51. The luminescence behavior was rationalized using quantum chemical density functional theory methods. The high emission efficiency of these tetragold(I) compounds and their good stability in film allowed for the fabrication of an organic electroluminescent device (OLED). Employing complex 5 (Φ = 0.51), an OLED was fabricated under a solution process to give a good external quantum efficiency of 3.1%, corresponding to a current efficiency of 6.1 cd/A and a power efficiency of 5.3 lm/W, with Commission Internationale de I’Eclairage coordinates of (0.52, 0.46).

A.V. Stepakov, A.G. Larina, V.M. Boitsov, A.P. Molchanov

“Reaction of 6,6-dimethylfulvene with aromatic imines in the presence of Lewis acids”

Russ. J. Org. Chem., 2014, 50,389-393 (russ. 404-408)

DOI: 10.1134/S1070428014030154

Formal aza-Diels-Alder (Povarov) reaction of 6,6-dimethylfulvene with aromatic imines is described for the first time.