Imidazolines Imidazoline- -2-thione

Conformational Equilibrium Data for Imidazoline-Thione and Thiobarbituric Acid Derivatives ... 

An adaptation of this reaction is the transformation of 3-substituted l-amino-4-oxo-imidazoline-2-thiones (282) into 2-alkylimino-5-aryl-3,6-dihydro-2//-l,3,4-thiadiazine-3-acetic esters, involving ring-scission of an imidazo[l,2-6]thiadiazine intermediate (283), occurs on treating the imidazoline thiones with a phenacyl bromide in hot alcohol solution <89S518>. The free bases (284) are liberated on heating the hydrobromides under reflux with triethylamine in ethanol. The thiadiazines (284) can also be synthesized independently from the A-(alkoxycarbonylmethyl) semicarbazides (R NHCSN(NH2)CH2C02Et) and phenacyl bromide. 

Aryl-5-oxo-3-trifluoromethyl-6,7-dihydroimidazo[2,3Y]l,3,5-thiadiazines 333 are formed by addition of 2-imidazoline thione 331 to 4-nitrophenyl-Y-alkylideneurethane 330. A requirement for the heterocyclization is the ability of the urethanes to generate intermediates 332 (Scheme 68) <2004CHE241>. 

Chiral imidazoUdin-2-thione or 2-one were prepared from o-glucoseamine by reaction with o,o -disubstituted arylisothiocyanates to give 39 which can be cycHzed to 40 [76]. Thus, a variety of derivatives were prepared carrying different aryl groups and as a consequence of hindered rotation, some of them exist as stable rotamers (Fig. 7). Treatment of 39 with acetic anhydride in pyridine at low temperature gave the respective per-O-acetyl derivative imidazolidine thione, which upon elimination of acetic acid gave the imidazoline thion 41 as a mixture of atropisomers [76]. 

Many mercaptoazoles exist predominantly as thiones. This behavior is analogous to that of the corresponding hydroxyazoles (c/. Section 4.02.3.7). Thus oxazoline-, thiazoline- and imidazoline-2-thiones (521) all exist as such, as do compounds of type (522). However, again analogously to the corresponding hydroxyl derivatives, other mercaptoazoles exist as such. 5-Mercaptothiazoles and 5-mercapto-l,2,3-triazoles (523), for example, are true SH compounds. 

Imidazoline, 2-phenyl-pKa, 5, 425 <69BSF4075, 73JCS(P2)1371) 4-Imidazoline-2-thione... 

Imidazoline-2-thione, 4,5-diphenyl-oxidation, 5, 405, 445 Imidazoline-2-thione, 4-methyl-Mannich reaction, S, 405 oxidation, 5, 445... 

Imidazoline-4-thione, 4,4-diaryl-rearrangement, S, 376 2-Imidazoline-4-thione, 5,5-diaryl-rearrangement, S, 376 2-Imidazoline-4-thione, 5,5-diphenyl-aromatization, 5, 422 2-Imidazoline-5-thione, 4,4-diaryl-rearrangement, 5, 376 2-Imidazoline-5-thione, 5,5-diaryl-rearrangement, S, 376 Imidazolinethiones acylation, S, 424 alkylation, S, 444 C NMR, S, 355... 

S-group removal from, S, 445 oxidation, S, 445 reactions, S, 443-445 reactivity, 5, 375-376 synthesis, S, 493 Imidazoline-2-thiones Mannich reaction, 5, 405 reactions, 5, 102, 443-444 with alkynes, 5, 444 synthesis, S, 493... 

However, the thione form of mereaptoazole ligands is retained in the metal eomplexes of l-methyl-l,3-imidazolin-2-thione 370 (90POL981) and 371 [92ICA75 93JOM(453)47], l-phenyltetrazol-5-thione 372 [96JOM (513)63] and l,3-thiazolidin-2-thione 373 (89ICA265). 

TOTWUU l,l -Methylenebis(S-iodine-3-methyl-4-imidazoline-2-thione) 2.683 2.897 175.71... 

X3 13C1N203S l-(p-Chlorophenyl)-4-o -D-erythrofuranosyl-4-imidazoline-2- thione CPEFIM 32 367... 

Gold(I) complexes with thiones are numerous and have several stoichiometries. The homoleptic [AuL2]+ have been obtained for L = imidazoline-2-thione,3029 4-amino-3-methyl-l,2,4-triazoline-5-thione 1560),3030 A -R-1,3-imidazoline-2-thione (R = Pr, Et),3031,3032 l,3-thiazoline-2-... 

Unsaturated five membered 2-chalcogenons with two heteroatoms at 1,3-positions (6) will show versatile reactivities with acceptors, since E in 6 must be very electron rich with the formation of a stable cyclic 671 electron system (6A).27,28 A saturated ring system 7 is expected to show similar trend due to the stabilization by the allylic X-C-Y framework with 471 electrons (7A). Arduengo reported the TBP formation of 1,3-dimethyl-4-imidazoline-2-thione (8), a typical example of 6 (X = Y = NMe and E = S), with bromine (8 Br2), together with the reactions.36... 

Lastly, the electrochemical reduction of 3-imidazolin-5-thiones in an AN solution showed a rather unexpected migration of the aryl group from nitrogen to sulfur [196] occurring under electron transfer, although the mechanism was not strictly proven by the authors (Scheme 40). 

Cyclic thiourea derivatives like l,3,4,5-tetramethylimidazole-2(3H)-thione— prepared by condensation of substituted thioureas with a-hydroxyketones—can be converted into the corresponding imidazolin-2-ylidene by desulfurization with sodium or potassium [Eq. (23)]. This method was used to prepare and isolate l,3-bis-neo-pentylbenzimidazolin-2-ylidene with Na/K. With LDA as the base it is also possible to generate free benzimidazolin-2-ylidenes in solution. ... 

---