A convenient procedure for introducing arylsulfanyl and heterylsulfanyl groups into the 5 position of the oxazole ring

Abstract

Available (2-aryl-5-mesyl-1,3-oxazol-5-yl)triphenylphosphonium salts readily react with sodium thiophenolates and their heterocyclic analogs by way of substitution of the mesyl group by an arylsulfanyl or a heterylsulfanyl group. Treatment of the products with sodium hydroxide results in their mild dephosphorylation, which was used for preparative synthesis of a series of 2-aryl-5-arylsulfanyl(heterylsulfanyl)-1,3-oxazoles.Previously we found that substituted vinylphosphonium salts of the general formula Cl 2 C=C . (NHCOR) + PPh 3 An ! regioselectively react with sodium sulfide to form stable mesomeric ylide betaines I and used the latter to success for preparing a series of 5-alkylsulfanyl-2-R-1,3-oxazoles [133]. In the present work, as seen from the scheme below, we studied the conversions of ylide betaines I, leading not only to S-methylation products II, but also to substituted oxazoles III3VII. The most important of the products were found to be new available reagents III containing adjacent mesyl and triphenylphosphonium groups in the oxazole ring. They readily and selectively reacted with sodium thiophenolates or their heterocyclic analogs, and this reaction proved to be a key step in the synthetic sequence III 6 V 6 VI 6 VII. As a result, we could introduce into the 5 position of the oxazole ring four types of sulfur-containing groups: ArS, HtS, ArSO 2 , and HtSO 2 . Furthermore, the 4-Ph 3 P + group could be replaced by hydrogen. The application scope of this convenient synthetic approach to 5-mercapto-1,3-oxazole derivatives is not restricted by the examples in the scheme below, since each of the steps of the sequence I 6 II 6 III 6 V is obviously rather general in nature. Moreover, this approach, even though it involves many steps, offers advantages over other known syntheses of a few representatives of phosphonium salts V, such as condensation of reagent IV and its analogs with thiols [3,4] or reaction of ylide betaines I with arenediazonium salts [3]. The latter method has a fairly narrow field of uses and, in addition, is insufficiently selective. The condensation IV 6 V occurs much more selectively, but the chlorination of ylide betaines I is complicated [3,4] and fails to provide isolable (2-aryl-5-chloro-1,3-oxazol-4-yl)triphenylphosphonium chlorides. Therefore, in the synthesis of phosphonium salts V, we considered it expedient to replace them by the available and analytically pure reagents III.In summary it can be said that the assignment of compounds I3VIII to 1,3-dioxazole derivatives casts no doubts, since the structure of one of the first members of the series of ylide betaines I with R = H, as well as its reaction product with methyl iodide was rigorously proved by X-ray diffraction analysis [5]. Moreover, successive treatment of ylide betaine Ia with hydrogen peroxide and sodium hydroxide gave 2-phenyl-1,3-dioxazole which was also synthesized by independent methods [2]. In addition, the modification of the 5-substituent was followed, as seen from Table 1, by 1 H NMR spectroscopy which gav...

In vitro and in silico study of 1,3-oxazol-4-yltriphenylphosphonium salts as potential inhibitors of Candida albicans transglycosylase

“…The structure of investigated 1,3-oxazole derivatives 1ad [26,27], 2 [27,22], 4 [28], 3a [29,30], 3b,c [21], 3d [26] and 3e [24] have been confirmed by NMR (1H and 13C NMR), IR spectroscopy, chromato-mass and elemental analysis and corresponded to previously described. Antimicrobial properties were determined by the disc diffusion method in Mueller-Hinton and Sabouraud agar [31].…”

“…The synthesis of 5-amino-and 5-sulfanyl-1,3-oxazol-4yl(triphenyl)phosphonium salts 1-4 was based on convenient approaches developed by B. S. Drach and coworkers [21][22][23]. 5-Alkylsulfanyl-1,3-oxazol-4yl(triphenyl)phosphonium iodides 1a-d were synthesized from available 1-acylamino-2,2-dichloroethenyl (triphenyl)phosphonium chlorides A of the general formula Cl2C=C(NHC(O)Ar)P + Ph3Cl - [21] by the reaction with sodium hydrosulfide followed by alkyl iodide treatment [21] (Scheme 1).…”

“…For the synthesis of 5-(4-chlorophenylsulfanyl)-2-(4methylphenyl)-1,3-oxazol-4-yl(triphenyl)phosphonium perchlorate (2) 2,2-dichloro-1-((4-methylbenzoyl)amino) ethenyl(triphenyl)phosphonium chloride A was converted into the corresponding ylide betaine B. The reaction of compound B with methyl iodide with subsequent hydrogen peroxide oxidation and sodium perchlorate treatment leads to 5-mesyl-substituted 1,3-oxazol-4-yl(triphenyl)phosphonium chloride C. By the substitution of mesyl group with sodium 4-chlorobenzenethiolate we obtained compound 2 [22] (Scheme 2).…”

Evaluation of Anticancer Activity of 1,3‐Oxazol‐4‐ylphosphonium Salts in Vitro

“…Yield 77 %, 4.94 g. Colorless solid, m.p. 193–195°C, (150–152 °C) [18] . IR (KBr): 2962, 2848, 1612, 1553, 1495, 1438, 1091 (ClO 4 − ), 996, 875, 805, 728, 688, 623, 566, 537, 516 cm −1 .…”

1,3-Oxazol-4-ylphosphonium salts as new non-peptide inhibitors of furin

“…[5-(4-Chlorophenylsulfonyl)-2-phenyl-1,3-oxazol-4-yl]triphenylphosphonium perchlorate (7) was synthesized following a procedure described in the literature [42].…”