- Reactions of thioketones with dichlorocarbene
-
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
-
-
Read Online
- Photochemistry of Dimethylthioketene Dimers
-
Thioketones and dithioesters, using 1,3-cyclobutanedithione and 3-mercapto-2,2,4-trimethyldithio-3-pentenoic acid β-thiolactone as models are found to undergo α-cleavage to give the diradical and carbene as reactive intermediates.
- Muthuramu, Kayambu,Ramamurthy, Vaidhyanathan
-
-
Read Online
- Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: Straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts
-
Adamantyloxyamine reacts with formaldehyde to give N-(adamantyloxy)formaldimine as a room-temperature-stable compound that exists in solution in monomeric form. This product was used for reactions with α-hydroxyiminoketones leading to a new class of 2-unsubstituted imidazole 3-oxides bearing the adamantyloxy substituent at N(1). Their reactions with 2,2,4,4-tetramethylcy-clobutane-1,3-dithione or with acetic acid anhydride occurred analogously to those of 1-alkylimidazole 3-oxides to give imidazol-2-thiones and imidazol-2-ones, respectively. Treatment of 1-(adamantyloxy)imidazole 3-oxides with Raney-Ni afforded the corresponding imidazole derivatives without cleavage of the N(1)–O bond. Finally, the O-alkylation reactions of the new imidazole N-oxides with 1-bromopentane or 1-bromododecane open access to diversely substituted, non-symmetric 1,3-dialkoxyimidazolium salts. Adamantyloxyamine reacts with glyoxal and formaldehyde in the presence of hydrobromic acid yielding symmetric 1,3-di(adamantyloxy)-1H-imidazolium bromide in good yield. Deprotonation of the latter with triethylamine in the presence of elemental sulfur allows the in situ generation of the corresponding imidazol-2-ylidene, which traps elemental sulfur yielding a 1,3-dihydro-2H-imidazole-2-thione as the final product.
- Mlostoń, Grzegorz,Celeda, Ma?gorzata,Urbaniak, Katarzyna,Jasiński, Marcin,Bakhonsky, Vladyslav,Schreiner, Peter R.,Heimgartner, Heinz
-
p. 497 - 505
(2019/03/08)
-
- Expected and unexpected results in reactions of fluorinated nitrile imines with (cyclo)aliphatic thioketones
-
A series of (cyclo)aliphatic thioketones have been tested towards trifluoroacetonitrile imines, generated in situ via base-induced dehydrohalogenation of the respective hydrazonoyl bromides. Typically, non-enolisable thioketones yielded exclusively 3-trif
- Utecht, Greta,Sioma, Justyna,Jasiński, Marcin,Mlostoń, Grzegorz
-
-
- Synthesis and selected reactions of hydrazides containing an imidazole moiety
-
The preparation of two types of imidazole derivatives bearing a hydrazide group was achieved by treatment of the corresponding esters with NH 2NH2·H2O in MeOH at room temperature. In the case of 4-(ethoxycarbonyl)-1H-imidazole 3-oxides 3, hydrazides of type 1 were formed with retention of the N-oxide structure (Scheme 1). Interestingly, due to a strong H-bonding, no deoxygenation of the N→O function could be achieved even by treatment of 3 with Raney-Ni. The second type, 2-[(1H-imidazol-2-yl)sulfanyl]acetohydrazides 2, was obtained from 1H-imidazole-2(3H)-thiones 4 in two steps via S-alkylation with methyl bromoacetate, followed by treatment with NH2NH2· H2O (Scheme 2). An imidazole 7, containing both types of hydrazide groups, was prepared analogously from ethyl 2,3-dihydro-2-thioxo-1H-imidazole-4- carboxylate 4d (Scheme 4). Both types of hydrazides, 1 and 2, were transformed successfully to the corresponding acylhydrazones 8 and 9, respectively (Scheme 5). Furthermore, it has been shown that hydrazides of type 1 are useful starting materials for the synthesis of 1,2,4-triazole-3-thiones 11 and 1,3,4-thiadiazole-2-amines 12, bearing an imidazole 3-oxide moiety (Scheme 7). Copyright
- Mlostoń, Grzegorz,Pieczonka, Adam Marek,Kowalczyk, Ewelina,Linden, Anthony,Heimgartner, Heinz
-
experimental part
p. 1764 - 1777
(2011/12/03)
-
- Addition reactions of sulfenyl and sulfinyl chlorides with 3-phenyl-1-azabicyclo[1.1.0]butane
-
The reactions of 3-phenyl-1-azabicyclo[1.1.0]butane with α-chlorosulfenyl chlorides and sulfinyl chlorides lead to the corresponding sulfenamides and sulfinamides, respectively, which possess an azetidine ring. It is proposed that a two-step mechanism occurs involving an intermediate carbenium ion, which is formed by the addition of the electrophile at the N-atom and cleavage of the N(1)-C(3) bond. The structures of 9b and 10b are established by X-ray crystallography.
- Mloston, Grzegorz,Woznicka, Marta,Drabowicz, Jozef,Linden, Anthony,Heimgartner, Heinz
-
experimental part
p. 1419 - 1429
(2009/02/07)
-
- Polycyclic [2+3]-cycloadducts from the thermal decomposition of bis(2,5-dihydro-1,3,4-thiadiazoles) in the presence of N-methylmaleimide
-
Thermal decomposition of a mixture of the two stereoisomeric bis(2,5-dihydro-1,3,4-thiadiazoles) cis- and trans-2, which was prepared by treatment of 2,2,4,4-tetramethylcyclobutane-1,3-dithione with excess of diazomethane in the presence of two equivalents of N-methylmaleimide, led to a mixture of three 1:2 cycloadducts of type 4. The structures of these thiocarbonyl methanide-adducts have been established by X-ray crystallography. In the presence of only one equivalent of N-methylmaleimide, a complex mixture of the three 1:2 adducts of type 4, the known dispirocyclic bis-thiiranes cis-and trans-3, and a 1:1 adduct 6, containing one thiirane ring and one fragment resulting from a [2+3]-cycloaddition of a thiocarbonyl methanide, was formed. The structure of the latter has again been proven by X-ray crystallography.
- Mloston,Celeda,Linden,Heimgartner
-
p. 2089 - 2099
(2007/10/03)
-
- Identification of regioisomers in a series of N-substituted pyridin-4-yl imidazole derivatives by regiospecific synthesis, GC/MS, and 1H NMR
-
The regiospecific synthesis of 2a (Scheme 3), a novel and potent pyridinyl imidazole inhibitor of p38 MAP (mitogen-activated protein) kinase, and the regioselective preparation of its regioisomer 2b (Scheme 4) are described. Chromatographic and spectroscopic data are presented, which in this class of compounds allow the unambiguous identification of regioisomers prepared by a nonregiospecific synthetic strategy. Biological data demonstrating the importance of the correct regiochemistry for inhibition of p38 are given.
- Wagner, Gerd K.,Kotschenreuther, Dunja,Zimmermann, Werner,Laufer, Stefan A.
-
p. 4527 - 4530
(2007/10/03)
-
- Thiones as superdipolarophiles. Rates and equilibria of nitrone cycloadditions to thioketones
-
1,3-Dipolar cycloadditions of N-methyl-C,C-diphenylnitrone (15) and N-methyl-C-phenylnitrone (16) with aliphatic thioketones are equilibrium reactions. The 1,4,2-oxathiazolidines were characterized and their dissociation constants measured by 1
- Huisgen, Rolf,Fisera, Lubor,Giera, Henry,Sustmann, Reiner
-
p. 9671 - 9678
(2007/10/02)
-
- Photolysis of the Dithiolactone 4-Isopropylidene-3,3-dimethyl-1-thiethan-2-thione; a Norrish Type I Reaction
-
The dithiolactone (1) upon excitation gives the dithione (2) in cyclohexane and other aprotic solvents and a 1:1 adduct in hydroxylic solvents from an n?* excited singlet state via an α-cleavage process.
- Muthuramu, K.,Ramamurthy, V.
-
p. 243 - 244
(2007/10/02)
-