ChemInform Abstract: Reaction of Acetophenone Oximes with Disulfur Dichloride; 4‐Aryl‐5‐arylimino‐1,2,3‐dithiazoles and Pentathiepino[6,7‐c]pyrrole.

Abstract

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Synthesis of 2-((2-(Benzo[d]oxazol-2-yl)-2H-imidazol-4-yl)amino)-phenols from 2-((5H-1,2,3-Dithiazol-5-ylidene)amino)phenols through Unprecedented Formation of Imidazole Ring from Two Methanimino Groups

“…The structure of the methanimines 9 has been confirmed by NMR and IR spectroscopy and mass-spectrometry and was unambiguously determined by an X-ray diffraction study of thienylmethanimine 9f ( Figure 1 ). Presumably, the formation of imines 9 and aroylbenzoxazoles 8 can be explained by the collapse of phenolic oxygen onto C-5 of the dithiazole ring with loss of HCl and sulfur followed by hydrolysis of methanimines 9 [ 28 ] . The difference in the result of reactions in methanol and ethanol can be explained by the higher stability of imine 8 in methanol; for example, NMR spectra of imines 8 were successfully obtained in deuteromethanol, while our attempts to obtain similar spectra in deuteroethanol failed due to their decomposition (hydrolysis).…”

“…4-Chlorosubtituted monocyclic 1,2,3-dithiazoles [ 1 , 2 , 3 , 17 , 18 , 19 , 20 ] were thoroughly investigated. The most interesting and valuable parts of this reactivity are various rearrangements of 4-chloro-1,2,3-dithiazoles, especially 5-arylimino derivatives (i.e., 2 ), which showed a great potential for the synthesis of multiple heterocycles, such as 1,2,4-thiadiazoles [ 21 ], isothiazoles [ 22 ], benzoxazines and benzothiazines [ 23 ], benzimidazoles [ 24 ], quinazolones [ 25 ], benzothiazoles [ 26 ] and benzoxazoles ( 3 , see Scheme 1 ) [ 26 , 27 , 28 ], and many others [ 1 , 2 , 29 , 30 ]. The formation of these heterocycles was the result of the presence of a chlorine atom at the C-4 position of the 1,2,3-dithiazole ring, which can be readily removed as a chloride anion.…”

“…Presumably, one might expect that the exchange of 4-chlorine atom in 1,2,3-dithiazoles to poorly leaving groups, such as aryl or hetaryl, can significantly change reaction results. There is only one example of the benzoxazole ring formation ( 5 ) from 2-((4-(4-nitrophenyl)-5 H -1,2,3-dithiazol-5-ylidene)amino)phenol 4 [ 28 ]. 4-Substituted 1,2,3-dithiazoles, except 4-chloro-1,2,3-dithiazoles, are much less available, and their chemistry still needs further developments.…”

The Conversion of 5,5′-Bi(1,2,3-dithiazolylidenes) into Isothiazolo[5,4-d]isothiazoles

“…Recently, Rakitin et al described the Cu(0)-mediated coupling of 4-substituted 5-chloro-1,2,3-dithiazolium chlorides 10 [20,21,22] to give ( E )-4,4′-disubstituted 5,5′-bi(1,2,3-dithiazolylidenes) 11 [23]. Products 11 are similar to ( E )-3,3′-bi(1,2-dithiolylidenes) 12 that undergo both thermal and light-mediated ring transformations to afford thieno[3,2- b ]thiophenes 13 [24] (Scheme 2).…”