Unexpected Formation of a Spiro Acridine and Fused Ring System from the Reaction between an <i>N</i>-Acridinylmethyl-Substituted Thiourea and Bromoacetonitrile under Basic Conditions

Klika, Karel D.; Bernát, Juraj; Imrich, Ján; Chomča, Igor; Sillanpää, Reijo; Pihlaja, Kalevi

doi:10.1021/jo001695p

Cited by 39 publications

(21 citation statements)

References 11 publications

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“…Thus, in contrast to similar structures, only ''minimal'' rapid fluxional mobility of the heterocycle and rotation about the N-3ϪC-9Ј bond is required to render the geminal H-5 protons and nuclei pairs of the anthracenyl moiety equivalent in solution. Although the crystallographic depiction of 3 is enantiomeric, this achiral compound did not crystallise in an enantiomeric space group as has been observed for a similar acridine derivative [20] and both enantiomorphs are present in the crystal structure.…”

Section: Structural Elucidationmentioning

confidence: 68%

“…Detailed experimental conditions have been described elsewhere previously. [20] 1D spectra consisted of normal proton and carbon, nitrogen (acquired with INEPT optimised on an n J HN value of 2 Hz), DEPT 135°, and NOE difference measurements; 2D spectra are comprised of DQF COSY, CHSHF ( 1 H-{ 13 C} with partial homonuclear decoupling in f1 and optimised on a 1 J HC coupling of 145 Hz) and HMBC ( 1 H-{ 13 C}, 1 H-{ 15 N}, both optimised on a long-range coupling of 8 Hz for both n J HC and n J HN ). Spectral widths and resolution were appropriately optimised from the 1D spectra and generally processed with zero-filling (ϫ2, ϫ4) and exponential weighting (plus a 2π/3-shifted sinebell function for the absolute-value mode spectra) applied in both dimensions prior to Fourier transformation.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Regioselective Synthesis of 2-Imino-1,3-thiazolidin-4-ones by Treatment ofN-(Anthracen-9-yl)-N′-ethylthiourea with Bromoacetic Acid Derivatives

et al. 2002

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The reaction between N-(anthracen-9-yl)-NЈ-ethylthiourea (1) and methyl bromoacetate yielded mainly 2-[(anthracen-9-yl)imino]-3-ethyl-1,3-thiazolidin-4-one (2), together with some of the regioisomeric 3-(anthracen-9-yl)-2-ethylimino-1,3-thiazolidin-4-one (3). The structures of the products were elucidated by NMR techniques and, for 3, X-ray crystallographic analysis. Treatment of 1 with bromoacetyl bromide again yielded 2 and 3, but with a reversed product distribution ratio, thus providing an interesting and unexpected re-

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Section: Structural Elucidationmentioning

confidence: 68%

Section: Methodsmentioning

confidence: 99%

Regioselective Synthesis of 2-Imino-1,3-thiazolidin-4-ones by Treatment ofN-(Anthracen-9-yl)-N′-ethylthiourea with Bromoacetic Acid Derivatives

et al. 2002

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“…Tautomerism, Regioisomerism, and Cyclization Reactions 639 of Acridinyl Thiosemicarbazides chain form (8) to undergo nucleophilic reaction with CH 3 I (or other electrophilic reagents) via the sulfur atom as this could conceivably be part of a concerted process yielding 10 directly (see Figure 1). Thus, it is probably inconsequential that the exchange rate between 8 and 9 was relatively slow and could not be observed by NMR experiments sensitive to exchange processes in contrast to the case of 2 and 4 which could be observed to undergo exchange.…”

Section: May-jun 2006mentioning

confidence: 99%

Tautomerism, regioisomerism, and cyclization reactions of acridinyl thiosemicarbazides

Klika

Balentová

Pihlaja

et al. 2006

Journal of Heterocyclic Chem

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The regioselectivities of methyl-and phenylhydrazine with acridin-9-yl isothiocyanate (thus yielding thiosemicarbazides with acridine substituted on the urea-type side) were examined. Methylhydrazine regioselectivity was high with the -nitrogen atom overwhelmingly more nucleophilic than the -nitrogen atom; phenylhydrazine regioselectivity was poor but varied with the solvent and only in the case of ethanol was nucleophilic predominance of the -nitrogen atom pronounced. Of note, whilst both phenyl thiosemicarbazides were present in solution only as spiro forms, the methyl product was present as an equilibrium mixture of open-chain and spiro thiosemicarbazides. Reactions on the NH 2 blocked analogue of methyl acridin-9-ylthiosemicarbazide (1-isopropylidene-2-methylthiosemicarbazide) were also examined. Interestingly, present in the starting material itself was a structural motif of novelty wherein a triazolethione represented the major species of an equilibrium between cyclic and open-chain forms.

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“…The important correlation between the NCH 3 protons and N-11 was negative, in accordance with a three-bond coupling for 1 H and 15 N. The two-bond coupling between the methyl protons and N-13 was, by comparison, positive. The treatment of 2/3 with CH 3 I and base was found to also provide an equilibrium of openchain S-methyl 1-(9,10-dihydroacridin-9-yliden)-2-methyl isothiosemicarbazide (8) and spiro 2´-methyl-3´-methylthiospiro[dihydroacridinyl-9(10H),5´-1´,2´-dihydro-1´,2´,4´-triazole] (9) forms in an 85:15 ratio, respectively (Scheme 4). Both products are clearly S-methylated based on the shielding of the introduced methyl group and a labile H resides on N-10 based on NOEs from H-10 to H-4 and H-5, which amounted to ca.…”

Section: Resultsmentioning

confidence: 98%

Structural revision of products resulting from the reaction of methylhydrazine with acridin-9-yl isothiocyanate due to unexpected acridinyl migration and further reactions

Klika¹,

Balentová²,

Bernát³

et al. 2007

Arkivoc

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The reaction of methyl acridin-9-ylthiosemicarbazide under basic conditions with methyl bromoacetate resulted in a 1,3-thiazolin-4-one structure as provided by X-ray crystallography. The structure forced a re-evaluation of the reactant methyl acridin-9-ylthiosemicarbazide, originally thought to be 2-methyl 4-acridin-9-ylthiosemicarbazide based on synthetic expectations, but which when examined by X-ray crystallography was found to be in fact the isomeric 2-methyl 1-acridin-9-ylthiosemicarbazide resulting from rearrangement via a spiro form which it is in equilibrium with in solution. The product resulting from reaction with methyl iodide was also studied and the previously reported semicarbazide produced by reaction with MNO was re-examined. In both cases, the 1,2 isomer rather than the 2,4 isomer was found to be present based on the sign of the 3 J CH3,N11 coupling. Full characterization of the compounds was rendered by 1 H, 13 C, and 15 N solution-state NMR, and in the solid state, by both 13 C and 15 N NMR.

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Unexpected Formation of a Spiro Acridine and Fused Ring System from the Reaction between an N-Acridinylmethyl-Substituted Thiourea and Bromoacetonitrile under Basic Conditions

Cited by 39 publications

References 11 publications

Regioselective Synthesis of 2-Imino-1,3-thiazolidin-4-ones by Treatment ofN-(Anthracen-9-yl)-N′-ethylthiourea with Bromoacetic Acid Derivatives

Regioselective Synthesis of 2-Imino-1,3-thiazolidin-4-ones by Treatment ofN-(Anthracen-9-yl)-N′-ethylthiourea with Bromoacetic Acid Derivatives

Tautomerism, regioisomerism, and cyclization reactions of acridinyl thiosemicarbazides

Structural revision of products resulting from the reaction of methylhydrazine with acridin-9-yl isothiocyanate due to unexpected acridinyl migration and further reactions

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