- Reactions of thioketones with a fluorinated thione S-imide
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N-(1-Adamantyl)hexafluorothioacetone S-imide (1) reacts readily with aromatic thioketones 4a-e to afford 1,4,2-dithiazolidines 5a-e as products of [3 + 2] dipolar cycloadditions. Unexpectedly, cycloadducts 5d and 5e, obtained from thioxanthione (4d) and 4,4′-(dimethoxy)thiobenzophenone (4e), respectively, are found to decompose at room temperature and could not be isolated as pure compounds. Unlike aromatic thiones, adamantanethione (4f) did not react with 1 at ambient temperature. However, reaction did occur upon heating in a sealed tube, and the new 1,4,2-dithiazolidine 9, bearing two adamantyl moieties, was isolated as the major product. The structure of 9 has been determined by X-ray diffraction analysis. The connectivity of the heterocyclic ring in this product indicates that the mechanism of its formation must proceed by a different route involving another in situ generated sulfur-centered 1,3-dipole. Retrocycloaddition of the primary adamantanethione cycloadduct 13 liberates hexafluorothioacetone, which is subsequently captured by Simide 1 to give tetrakis(trifluoromethyl)-1,4,2-dithiazolidine 8 as a crystalline product. The structure of 8 has also been confirmed by X-ray diffraction analysis.
- Mloston, Grzegorz,Celeda, Malgorzata,Roesky, Herbert W.,Parisini, Emilio,Ahlemann, Jens-Thomas
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Read Online
- Controlling the speed of rotation in molecular motors. Dramatic acceleration of the rotary motion by structural modification
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Substitution of a 6-membered by a 5-membered ring upper half in the light driven second generation molecular motors resulted in a dramatic increase of the speed of rotation. The Royal Society of Chemistry 2005.
- Vicario, Javier,Meetsma, Auke,Feringa, Ben L.
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Read Online
- New procedure for the preparation of highly sterically hindered alkenes using a hypervalent iodine reagent
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A method to construct the olefinic bond in overcrowded alkenes using hypervalent iodine reagent was discussed. In the process, the diazo compound was made to react in a 1,3-dipolar cycloaddition with thioketone to form two isomeric thiadiazolines, which were unstable. A single isomer of episulfide was formed, since the methyl substituent blocks ring closure on one side of the molecule of the essentially flat thiocarbonyl yielded moiety. The method is very efficient because it allows selective coupling reaction and facilitates purification of the desired product.
- Ter Wiel, Matthijs K. J.,Vicario, Javier,Davey, Stephen G.,Meetsma, Auke,Feringa, Ben L.
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Read Online
- Generation of “Sumanenylidene”: A Ground-State Triplet Carbene on a Curved π-Conjugated Periphery
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We have observed the generation of sumanenylidene (2), a divalent, neutral-carbon species at the benzylic position of sumanene (1). We also clarified both experimentally and theoretically that the ground state of compound 2 was a triplet state and that its singlet–triplet energy gap (ΔEST) was similar to that in fluorenylidene. The curved structure of compound 2 led to slightly better spin delocalization over the two adjacent aromatic rings than in planar systems, because of the unpaired spins on the σ and π orbitals. Synthetic application of the carbene precursor, diazosumanene (5), with a variety of thiocarbonyl compounds revealed its utility for the preparation of tetrasubstituted alkene compounds (e.g., that contain a strongly electron-donating unit) that are directly conjugated to the sumanene (1) moiety.
- Yakiyama, Yumi,Wang, Yufeng,Hatano, Sayaka,Abe, Manabu,Sakurai, Hidehiro
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supporting information
p. 1844 - 1848
(2019/02/24)
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- One-Pot Catalytic Cleavage of C=S Double Bonds by Pd Catalysts at Room Temperature
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The C=S double bonds in CS2 and thioketones were catalytically cleaved by Pd dimeric complexes [(N∧N)2Pd2(NO3)2](NO3)2 (N∧N, 2,2′-bipyridine, 4,4′-dimethylbipyridine or 4,4′-bis(trifluoromethyl)) at room temperature in one pot to afford CO2 and ketones, respectively, for the first time. The mechanisms were fully investigated by kinetic NMR, isotope-labeled experiments, in situ ESI-MS, and DFT calculations. The reaction is involved a hydrolytic desulfurization process to generate C=O double bonds and a trinuclear cluster, which plays a pivotal role in the catalytic cycle to regenerate the dimeric catalysts with HNO3. Furthermore, the electronic properties of catalyst ligands possess significant influence on reaction rates and kinetic parameters. At the same temperature, the reaction rate is consistent with the order of electronegativity of N∧N ligands (4,4′-bis(trifluoromethyl) > 2,2′-bipyridine > 4,4′-dimethylbipyridine). This homogeneous catalytic reaction features mild conditions, a broad substrate scope, and operational simplicity, affording insight into the mechanism of catalytic activation of carbon sulfur bonds.
- Zhu, Ting,Wu, Xiaoxi,Yang, Xinzheng,Sharma, Bigyan,Li, Na,Huang, Jiaming,Wang, Wentao,Xing, Wang,Zhao, Zhenwen,Huang, Hui
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supporting information
p. 9266 - 9273
(2018/08/17)
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- Central-to-Helical-to-Axial-to-Central Transfer of Chirality with a Photoresponsive Catalyst
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Recent advances in molecular design have displayed striking examples of dynamic chirality transfer between various elements of chirality, e.g., from central to either helical or axial chirality and vice versa. While considerable progress in atroposelective synthesis has been made, it is intriguing to design chiral molecular switches able to provide selective and dynamic control of axial chirality with an external stimulus to modulate stereochemical functions. Here, we report the synthesis and characterization of a photoresponsive bis(2-phenol)-substituted molecular switch 1. The unique design exhibits a dynamic hybrid central-helical-axial transfer of chirality. The change of preferential axial chirality in the biaryl motif is coupled to the reversible switching of helicity of the overcrowded alkene core, dictated by the fixed stereogenic center. The potential for dynamic control of axial chirality was demonstrated by using (R)-1 as switchable catalyst to direct the stereochemical outcome of the catalytic enantioselective addition of diethylzinc to aromatic aldehydes, with successful reversal of enantioselectivity for several substrates.
- Pizzolato, Stefano F.,?tacko, Peter,Kistemaker, Jos C. M.,Van Leeuwen, Thomas,Otten, Edwin,Feringa, Ben L.
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supporting information
p. 17278 - 17289
(2019/01/04)
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- Bifunctional Molecular Photoswitches Based on Overcrowded Alkenes for Dynamic Control of Catalytic Activity in Michael Addition Reactions
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The emerging field of artificial photoswitchable catalysis has recently shown striking examples of functional light-responsive systems allowing for dynamic control of activity and selectivity in organocatalysis and metal-catalysed transformations. While o
- Pizzolato, Stefano F.,Collins, Beatrice S. L.,van Leeuwen, Thomas,Feringa, Ben L.
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supporting information
p. 6174 - 6184
(2017/05/05)
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- A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes
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Trimethylsilyldiazomethane (TMS-CHN2) reacts readily with hetaryl thioketones to give sterically crowded 2-trimethylsilyl- 4,4,5,5-tetrahetaryl-1,3-dithiolanes with complete regioselectivity at -75 °C as well as at rt. Thiofluorenone, a relatively stable and highly reactive aryl thioketone, yields upon treatment with TMS-CHN2at -60 °C the corresponding 1,3,4-thiadiazoline. This unstable cycloadduct undergoes decomposition at ca. -45 °C and the silylated thiocarbonyl S-methanide generated thereby is trapped with complete regioselectivity by aryl or hetaryl thioketones forming also sterically crowded 2-trimethylsilyl-1,3- dithiolanes. The obtained 1,3-dithiolanes, by treatment with an equimolar amount of TBAF in a one-pot procedure, are converted in high yields into hetaryl/aryl-substituted ethenes or dibenzofulvenes, respectively, via a cycloreversion reaction of the intermediate 1,3-dithiolane carbanion. The presented protocol offers a new, highly efficient approach to tetrasubstituted ethenes and dibenzofulvenes bearing aryl and/or hetaryl substituents.
- Mloston, Grzegorz,Pipiak, Paulina,Hamera-Fa?dyga, Róza,Heimgartner, Heinz
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p. 1900 - 1906
(2017/09/27)
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- Trifluoromethylated 2,3-dihydro-1,3,4-thiadiazoles via the regioselective [3+2]-cycloadditions of fluorinated nitrile imines with aryl, hetaryl, and ferrocenyl thioketones
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A series of hydrazonoyl bromides prepared from readily available N-arylhydrazones of fluoral was used for the in situ generation of fluorinated nitrile imines. These 1,3-dipoles were efficiently trapped with aryl and hetaryl thioketones yielding fluoromet
- Mlostoń, Grzegorz,Urbaniak, Katarzyna,Utecht, Greta,Lentz, Dieter,Jasiński, Marcin
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p. 147 - 154
(2016/11/25)
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- Thermal [2+2]-cycloadditions of diphenylketene with aryl- and hetaryl-substituted thioketones
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The reaction of diphenylketene (1) with aryl- and hetaryl-substituted thioketones (2) gave the corresponding 3,3,4,4-tetraarylthietan-2-ones (3) in good yields. Remarkably, the reactions with bis-hetaryl-substituted thioketones occurred significantly faster compared with those involving the bis-aryl-substituted thioketones. The structure of compound 3c has been established by X-ray crystallography.
- Mlosto, Grzegorz,Urbaniak, Katarzyna,Szychowska, Anna,Linden, Anthony,Heimgartner, Heinz
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p. 529 - 539
(2015/03/04)
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- Studies on the reactions of thiocarbonyl S-methanides with hetaryl thioketones
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Dihetaryl thioketones react with thiocarbonyl ylides to give 1,3-dithiolanes in high yields. No competitive side reactions of the thiocarbonyl ylides were observed, evidencing the 'superdipolarophilic' character of this less-known group of thioketones. De
- Mlostoń, Grzegorz,Pipiak, Paulina,Linden, Anthony,Heimgartner, Heinz
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p. 462 - 473
(2015/04/27)
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- Variations of bistricyclic aromatic enes: Mono-bridged tetraarylethene naphthologs
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The syntheses, molecular and crystal structures, NMR spectroscopic study, and DFT computational study of naphthologs of mono-bridged (X = -, O, S, Se, and Te) tetraarylethene (BAE-1s) 11-25 with α,α-, β,β-, and α,β-dinaphthalenyl substituents have been reported. The BAE-1s have been prepared by Barton-Kellog twofold extrusion from the respective chalcogenothiones and diazomethylenebisnaphthylenes. Complete assignments of 1H- and 13C-NMR spectra of 11-25 have been made through 2-dimensional correlation spectroscopy (DQF-COSY, HSQC, HMBC, and NOESY). The corresponding intermediates, thiiranes 33-47, have been also isolated (except 38), and their molecular and crystal structures have been determined. The molecular structures of BAE-1s 12-15, 20, and 22-25 adopted folded-twisted conformations with considerably folded (φ = 30°-57°) tricyclic moieties. The α,α- and α,β-dinaphthalenyl derivatives are more overcrowded than β,β-dinaphthalenyl derivatives. The relief of the steric strain due to the overcrowding around C9 = C9' caused by the presence of naphthalenyl substituents was achieved by their twisting around the single bonds that connect the α-naphthalenyl and β-naphthalenyl moieties to C9'. The 1H-NMR spectra have shown shielding of H2, H7 of 11-25 and the pronounced deshielding of H8', H8′ of α,α-dinaphthalenyl-substituted BAE-1s 13-15 in contrast to β,β-dinaphthalenyl-substituted BAE-1s 16-20. The upfield shifts of H2, H7 suggested conformations in which these hydrogens are located above the planes of the opposing naphthalene rings. DFT calculations of 11-20 have been performed at B3LYP/6-31G(d) and B3LYP/SDD. The results have shown that the global minima of BAE-1s without a chalcogen bridge 11 and 16 are twisted (-sc,-sc)-C 2-t conformations. The global minima of BAE-1s with a chalcogen bridge are folded-twisted (-sc,-ac)-C 1-ft conformations for α,α-dinaphthalenyl-substituted BAE-1s 12-15 and either anti- or syn-(-sc,ac)-C 1-ft conformations for β,β-dinaphthalenyl-substituted BAE-1s 17-20. The pronounced differences between the α,α-dinaphthalenyl and the β,β-dinaphthalenyl derivatives are noted. Dispersion-corrected B3LYP calculations stabilize significantly the α,α-dinaphthalenyl derivatives versus the β,β-dinaphthalenyl derivatives. The geometrical parameters of BAEs-1 11-15 and 20, derived from their molecular X-ray structures and from their B3LYP-optimized geometries are in a good agreement.
- Assadi, Naela,Pogodin, Sergey,Cohen, Shmuel,Agranat, Israel
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p. 319 - 352
(2015/01/30)
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- An enantioselective synthetic route toward second-generation light-driven rotary molecular motors
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(Chemical Equation Presented) Controlling the unidirectional rotary process of second-generationmolecular motors demands access to these motors in their enantiomerically pure form. In this paper, we describe an enantioselective route to three new second-generation light-driven molecular motors. Their synthesis starts with the preparation of an optically active R-methoxy-substituted upper-half ketone involving an enzymatic resolution. The subsequent conversion of this ketone to the corresponding hydrazone by treatment with hydrazine led to full racemization. However, conversion to a TBDMS-protected hydrazone by treatment with bis-TBDMS hydrazine, prepared according to a new procedure, proceeds with nearly full retention of the stereochemical integrity. Oxidation of the TBDMS-protected hydrazone and subsequent coupling to a lower-half thioketone followed by recrystallization provided the molecular motors with >99% ee. As these are the first molecular motors that have a methoxy substituent at the stereogenic center, the photochemical and thermal isomerization steps involved in the rotary cycle of one of these new molecules were studied in detail with various spectroscopic techniques.
- Pijper, Thomas C.,Pijper, Dirk,Pollard, Michael M.,Dumur, Frederic,Davey, Stephen G.,Meetsma, Auke,Feringa, Ben L.
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experimental part
p. 825 - 838
(2010/06/12)
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- A Trimer of ultrafast nanomotors: synthesis, photochemistry and self-assembly on graphite
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A molecular motor trimer which was found to form self-assembled monolayers at the interface between the surface of highly oriented pyrolytic graphite (HOPG) and the solvent (1-phenyloctane) was reported. The structure of the stable arrays was determined by means of STM at the liquid/solid interface. The motor trimer were synthesized in one step by Sonogashira coupling with phenyl acetylene and 1,3,5-triethynylbenzene respectively. Enantioresolution was performed with chiral stationary phase HPLC. The cis and trans isomers and their configuration was assigned by using H NMR and NOE spectroscopy. The kinetic parameters of the thermal helix inversion of motor were determined by monitoring its CD absorption at λ = 218 nm over time in the dark at four different temperatures ranging from 167.5 to 175 K. Molecular motor trimer was found to form organized arrays of molecules by self-assembly at the phenyloctane/HOPG interface.
- Cnossen, Arjen,Pijper, Dirk,Kudernac, Tibor,Pollard, Michael M.,Katsonis, Nathalie,Feringa, Ben L.
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supporting information; experimental part
p. 2768 - 2772
(2009/12/04)
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- Reactions of 9H-fluorene-9-thione with (trimethylsilyl)diazomethane
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The [3+2]-cycloaddition of (trimethylsilyl)diazomethane (7) with 9H-fiuorene-9-thione (1) at -60°C yields the spirocyclic 2,5-dihydro-5-trimethylsilyl-1,3,4-thiadiazole 10, which eliminates nitrogen at room temperature to give the 1,4-dithiane derivative
- Mloston,Urbaniak,Linden,Heimgartner
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p. 1849 - 1860
(2008/09/18)
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- Reactions of α-diazocamphor with aromatic thioketones
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The reactions of α-diazocamphor (6) with aromatic thioketones (9a-d) in dichloromethane at room temperature afforded mixtures of the stereoisomeric spirocyclic thiiranes (10) and (11). A reaction mechanism via [2+3] cycloaddition to give the spirocyclic 2,5-dihydro-1,3,4-thiadiazoles (13) and (14), subsequent elimination of nitrogen and 1,3-dipolar electrocyclization of the intermediate thiocarbonyl ylide (15) is proposed. The structure of the stereoisomers (10a) and (11a) has been established by X-Ray crystallography. Desulfurization of the mixtures (10/11) with triphenylphosphane in boiling THF yielded the alkylidene derivatives (12).
- Mloston, Grzegorz,Celeda, Malgorzata,Linden, Anthony,Heimgartner, Heinz
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- Fine tuning of the rotary motion by structural modification in light-driven unidirectional molecular motors
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The introduction of bulky substituents at the stereogenic center of light-driven second-generation molecular motors results in an acceleration of the speed of rotation. This is due to a more strained structure with elongated C=C bonds and a higher energy
- Vicario, Javier,Walko, Martin,Meetsma, Auke,Feringa, Ben L.
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p. 5127 - 5135
(2007/10/03)
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- Microwave-accelerated solvent-free synthesis of thioketones, thiolactones, thioamides, thionoesters, and thioflavonoids
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Formula presented An expeditious, solvent-free, and high yield conversion of ketones, flavones, isoflavones, lactones, amides, and esters to the corresponding thio analogues is described utilizing Lawesson's reagent in a process that circumvents the use of dry solvents and excess of the reagent.
- Varma, Rajender S.,Kumar, Dalip
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p. 697 - 700
(2008/02/11)
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- Reactions of thioketones with dichlorocarbene
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The reactions of sterically crowded cycloalkanethiones of type 2 with CHCl3/NaOH under phase-transfer catalysis (PTC) with benzyl(triethyl)ammonium chloride (TEBA) as catalyst afforded the corresponding 'gem.-dichlorothiiranes' of type 3 in good yields (cf. Scheme 2 and Table). The desulfurization, which, in some cases, occurred spontaneously, led to (dichloromethylidene)cycloalkanes of type 4. Similar results were obtained using Seyferth's reagent in boiling benzene. In the case of 2,2,6,6-tetramethylcyclohexanethione, reaction under PTC conditions after 3 h yielded only the corresponding dichloromethylidene derivative; on the other hand, workup after 1 h gave (2,2,6,6- tetramethylcyclohexylidene)methanethione (thioketene 9; Scheme 5).
- Mloston, Grzegorz,Romanski, Jaroslaw,Swiatek, Anna,Heimgartner, Heinz
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p. 946 - 956
(2007/10/03)
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- Laser flash photolysis studies of oxygen and sulfur atom transfer reactions from oxiranes and thiiranes to singlet carbenes
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Laser flash photolysis (UV-LFP) studies of benzylchlorodiazirine (1a), phenylchlorodiazirine (1b), phenylmethoxydiazirine (1c), 2,2-dimethoxy-5,5- dimethyl-Δ3-1,3,4-oxadiazoline (6a), 3,4-diaza-2,2-dimethoxy 1- oxa[4.3]spirooct-3-ene (6b), 5',5'-dimethoxyspiro[adamantane]-2,2 -[Δ3- 1,3,4-oxadiazoline] (6c), and diazofluorene (DAF) in the presence of oxiranes and thiiranes are reported. These compounds, upon irradiation, afford benzylchlorocarbene (2a), phenylchlorocarbene (2b), methoxyphenylcarbene (2c), dimethylcarbene (8a), cyclobutylidene (8b), adamantylidene (8c), and fluorenylidene (FL), respectively. Absolute rate constants for the transfer of oxygen and sulfur atoms to these carbenes have been determined in both acetonitrile and cyclohexane solvents. These carbenes abstract oxygen and sulfur atoms with bimolecular rate constants ranging from 104 to 1010 M- 1 s-1 at 22 °C. Ylides from attack of carbenes onto heteroatom donors were not observed for any of the heteroatom transfer reactions. It was found that the magnitudes of the rate constants for heteroatom transfer are dependent on the philicity of the carbene intermediate, and trends in the kinetic data suggest that oxygen and sulfur atom transfers occur by concerted mechanisms through ylide-like transition states. The reactions of dimethoxycarbene (14) with cyclohexene oxide and propylene sulfide have been studied by the thermolysis of 6a, in benzene, at 110 °C. It was found that dimethoxycarbene also abstracts oxygen and sulfur atoms, albeit in low yields. It is concluded that, for singlet carbenes, carbene electrophiiicity is important in these heteroatom transfer processes.
- Pezacki, John Paul,Wood, Paul D.,Gadosy, Timothy A.,Lusztyk, Janusz,Warkentin, John
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p. 8681 - 8691
(2007/10/03)
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- Photochemical reactions of bianthrone and related substances
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Photocleavage reactions of a wide range of ethylene compounds were investigated. Photosensitized oxygenation resulted in formation of their corresponding ketones. On the other hand, photoreaction of these substrates with elemental sulfur yielded the corresponding thioketones. Furthermore, photobehaviour of some ethylene episulfides also was studied. It could be concluded that UV-irradiation provides a rapid and effective desactivation pathway for this class of compounds.
- Abdou, Wafaa M.,Elkhoshnieh, Yehia O.,Sidky, Mahmoud M.
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p. 3595 - 3602
(2007/10/02)
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- Silicon-Assisted Synthesis of Thiocarbonyl Derivatives and Reactivity of Dienophilic Thioaldehydes
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Treatment of bis(trimethylsilyl) sulfide with CoCl2 * 6 H2O in the presence of aldehydes affords the corresponding thiocarbonyl analogues which can be trapped to avoid polymerization.The sulfurization reaction also takes place in the presence of TfOSiMe3, in which case, besides thioaldehydes, thioketones may be obtained in satisfactory yields.When thioaldehydes are generated with the CoCl2 * 6 H2O method the Diels-Alder reaction with cyclohexadiene occurs with very high selectivity in favor of the endo isomer, whereas when the TfOSiMe3-based method is employed, the stereochemistry of the cycloadduct can be conveniently selected toward endo or exo by varying the molar ratio of the sulfurating agent.
- Capperucci, Antonella,Degl'Innocenti, Alessandro,Ricci, Alfredo,Mordini, Alessandro,Reginato, Gianna
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p. 7323 - 7328
(2007/10/02)
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- Synthesis of Highly Pure Rubicene and Rubicene Derivatives
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A simple one-step synthesis of highly pure rubicene (2) from fluorenone (1) and magnesium with 24percent yield is described and compared with other preparation procedures.Mono- and di-substituted rubicene derivatives are prepared by electrophilic aromatic substitution.
- Sachweh, Volker,Langhals, Heinz
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p. 1981 - 1987
(2007/10/02)
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- STUDIES ON ORGANOPHOSPHORUS COMPOUNDS-XL. REACTIONS OF KETONES WITH 2,4-BIS(4-METHOXYPHENYL)-1,3,2,4-DITHIADIPHOSPHETANE 2,4-DISULFIDE
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Cyclohexanone and cyclopentanone react with (2,4-bis-4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson Reagent (LR)) at 80 deg C with formation of new spiro-1,3,5,2-trithiaphosphorines 1 and 2, respectively. 2-Methyl and 2-phenylcyclohexanone also react with LR at 80 deg C producing the enethiols 3 and 4, which on storage are transformed into the sulfides 5 and 6.Unsaturated cyclohexanones 7-9 are transformed into the corresponding thioketones 10-12 after reactions with LR at 60 deg C for a few hours. 2-Hydroxyketones react with LR with formation of 1,3,2-oxathiaphospholes and similarly a 2-aminoketone gave a 1,3,2-thiazaphosphole.Aromatic ketones, reacted with LR to give corresponding thioketones.Thiofluorenone dimerized to form the cyclic disulfide 31, as proved by X-ray analyses.
- Scheibye, S.,Shabana, R.,Lawesson, S.-O.,Romming, C.
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p. 993 - 1002
(2007/10/02)
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