Synthesis of [2.2.3]Cyclazines, Aza[2.2.3]cyclazines and Their Related Compounds

Tominaga, Yoshinori; Shiroshita, Yoshihide; Hosomi, Akíra

doi:10.3987/rev-88-395

Cited by 40 publications

(14 citation statements)

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“…N[2.2.3] has been early synthesized by Boekelheide and coworkers, [48,49] the UV‐Vis [7] and the proton NMR spectra [6] have been recorded and the aromaticity assigned; the effect of benzo‐annelation on the extent of aromaticity was a special topic and widely studied [4,5, 50−56] . Also various aza‐analogues of N[2.2.3] were classified accordingly (e. g. Figure S1–Supporting Information) [17,57–59] and the complex 1 H and 13 C NMR spectra completely assigned by Castle et al [60,61] .…”

Section: Resultsmentioning

confidence: 99%

Cyclazines‐Structure and Aromaticity or Antiaromaticity on the Magnetic Criterion

Kleinpeter

Koch

2022

Eur J Org Chem

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Structure and spatial magnetic properties, through‐space NMR shieldings (TSNMRSs), of all ten cycl[2.2.2]azine to cycl[4.4.4]azine, hetero‐analogues and the corresponding hydrocarbons have been calculated at the B3LYP/6‐311G(d,p) theory level using the GIAO perturbation method and employing the nucleus independent chemical shift (NICS) concept. The TSNMRS values (actually, the ring current effect as measurable in 1H NMR spectroscopy) are visualized as iso‐chemical‐shielding surfaces (ICSS) of various size and direction, and employed to readily qualify and quantify the degree of (anti)aromaticity. Results are confirmed by NMR [δ(1H)/ppm, δ(15N)/ppm] and geometry (planar, twisted, bow‐shaped) data. The cyclazines N[2.2.2]− up to N[2.4.4]− are planar or at most slightly bowl‐shaped and, due to coherent peripheral ring currents (except in N[2.3.3]−, N[2.3.4], N[3.3.4]+ and N[2.4.4]+), develop aromaticity or anti‐aromaticity of the whole molecules dependent on the number of peripheral conjugated π electrons. The cyclazines N[2.3.3]−, N[2.3.4], N[3.3.4]+ and N[2.4.4]+ develop two ring currents of different direction within the same molecule, in which the dominating ring current proves to be paratropic (in N[3.3.4]+ diatropic) including the nodal N pz lone pair into the conjugation. The residual cyclazines N[3.4.4], N[4.4.4]− and N[4.4.4]+ are heavily twisted and, therefore, are not developing peripheral or diverse ring currents. The TSNMRS information about cyclazines and the parent tricyclic annulene analogues is congruent subject to structure and number of peripheral or internal conjugated π electrons, the corresponding (anti)aromaticity is in unequivocal accordance with Hückel's rule.

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Section: Resultsmentioning

confidence: 99%

Cyclazines‐Structure and Aromaticity or Antiaromaticity on the Magnetic Criterion

Kleinpeter

Koch

2022

Eur J Org Chem

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“…Benzoannulated [2.2.3]cyclazines (32b, c) present decreased diatropicity as compared to the corresponding nonbenzannulated parent system (32a) based on the results of NMR studies [19]. The present section describes the synthesis of new polymethine dyes with a pyrrole ring as a heterocycle incorporated into the methine chain, as shown in Figure 4 [20]…”

Section: May-jun 2002 579mentioning

confidence: 99%

ChemInform Abstract: Synthesis of Methylthiomaleimides for the Preparation of Pyridazines and Related Compounds.

2002

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New functionalized maleimides (3-methylthio-2,5-dioxo-1H-pyrroles) were obtained by the reaction of ketene dithioacetals with nitromethane or the reaction of nitro ketene dithioacetal with active methylene compounds in the presence of the appropriate base in dimethyl sulfoxide followed by treatment with methanol.These maleimides reacted with various nucleophilic reagents such as electron-rich aromatic and heteroaromatic compounds like dialkylanilines, aminophenols, indoles, indolizines, and cyalazines to give the corresponding 3-aryl-or heteroaryl-1H-pyrole-2,5-diones. Styryl and merocyanine dyes, and polycyclic pyridazine-diones as chemiluminophors and succinimides were also obtained from these maleimides with good results.

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“…Hexyl Carbamimidothioate Hydrobromide (3a). According to Method A, with l a (18.56 g, 0.1 12 mol), 2 (5.71 g, 0.075 mol), and EtOH (50 ml): 17 (7 9). According to Method B (Procedure 2), with 3 g (0.306 g, 1.29 mmol), 6 (0.20 g, 1.17 mmol), and (i-Pr),EtN (0.5 ml, 2.92 mmol): 0.29 g (78%) of7g.…”

Section: Experimental Partmentioning

confidence: 99%

A Novel Solution‐ and Solid‐Phase Approach to 2,4,5‐tri‐ and 2,4,5,6‐tetrasubstituted pyrimidines and their conversion into condensed heterocycles

Masquelin

Sprenger

Baer

et al. 1998

Helvetica Chimica Acta

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A novel general synthesis of 2,4,5-tri-and 2,4,5,6-tetrasubstituted pyrimidines 5a-d and 7a, e, f, g by condensation of thiouronium salts of type 3 with (ethoxymethy1idene)malononitrile (4) and [bis(methylthio)methylidene]malononitrile (6), respectively, was first established in solution (Scheme f) and successfully transferred onto solid support by using the polymer-bound thiouronium salt 11 (Scheme 3). Further investigations were directed toward a multidirectional cleavage procedure of the 2-(alkylsulfinyl) intermediates, obtained from the 2-(alky1thio)pyrimidines 7a (Scheme 2) or 12 and 14 (Schemes 3 and 4), with different nucleophiles to form highly substituted pyrimidines. In addition, fused-heterocycle derivatives 22a-h, 24a-c, and 26a-e were generated in good-to-excellent yields by condensation of 7a, e, h with versatile isocyanates and isothiocyanates, with subsequent alkylation (Scheme 5).

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Synthesis of [2.2.3]Cyclazines, Aza[2.2.3]cyclazines and Their Related Compounds

Cited by 40 publications

References 0 publications

Cyclazines‐Structure and Aromaticity or Antiaromaticity on the Magnetic Criterion

Cyclazines‐Structure and Aromaticity or Antiaromaticity on the Magnetic Criterion

ChemInform Abstract: Synthesis of Methylthiomaleimides for the Preparation of Pyridazines and Related Compounds.

A Novel Solution‐ and Solid‐Phase Approach to 2,4,5‐tri‐ and 2,4,5,6‐tetrasubstituted pyrimidines and their conversion into condensed heterocycles

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