Formation of bis[-(N-substituted cyanamino)phenyl] disulfides by photolysis of 3-substituted 2-nitrosoimino-2, 3-dihydrobenzothiazoles

Akiba, Kin‐ya; Fukawa, Isaburo; Mashita, Kentaro; Inamoto, Naoki

doi:10.1016/s0040-4039(00)75647-4

Cited by 4 publications

(6 citation statements)

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“…Although accurate calculation of radicals is difficult, these results suggest that homolysis is not a facile process. The ring-opened radical 13 is calculated to be 6.3 kcal/mol more stable than 12 , consistent with the observation of ring-opened products in the photochemistry of 2 (eq 3) …”

Section: Methodssupporting

confidence: 83%

“…Furthermore, the products are not consistent with those expected from a radical pathway, such as appears to be operative in the photochemical deazetization of 2. 12 Finally, the activation entropies, ∆S q of 1.3 eu in cyclohexane and of -12.9 eu in methanol, are inconsistent with the large and positive activation entropy anticipated for a fragmentation reaction. Thus, all of these results are consistent with the mechanism presented in eq 2.…”

Section: Resultsmentioning

confidence: 96%

“…Photolysis of the strongly colored nitrosimines, such 2a , gives rise to a variety of products that appear to have come from loss of NO and subsequent radical reactions (eq 3) . Similar products, indicative of radical reactions, are also observed in the thermolysis of sterically hindered nitrosimines (e.g., 1 , with R 1 = t -Bu and R 2 = 2-MePh) .…”

Section: Introductionmentioning

confidence: 82%

“…The ring-opened radical 13 is calculated to be 6.3 kcal/mol more stable than 12, consistent with the observation of ring-opened products in the photochemistry of 2 (eq 3). 12 We located transition states for the isomerization of 9a to 9a′ and of 9a(out) to 9a(out)′. These both correspond to rotations around the C 2 dN 6 bond.…”

Section: Methodsmentioning

confidence: 99%

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Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines¹

et al. 2001

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A series of substituted 2-nitrosiminobenzothiazolines (2) were synthesized by the nitrosation of the corresponding 2-iminobenzothiazolines (6). Thermal decomposition of 2a--f and of the seleno analogue 7 in methanol and of 3-methyl-2-nitrosobenzothiazoline (2a) in acetonitrile, 1,4-dioxane, and cyclohexane followed first-order kinetics. The activation parameters for thermal deazetization of 2a were measured in cyclohexane (Delta H(++) = 25.3 +/- 0.5 kcal/mol, Delta S(++) = 1.3 +/- 1.5 eu) and in methanol (Delta H(++) = 22.5 +/- 0.7 kcal/mol, Delta S(++) = -12.9 +/- 2.1 eu). These results indicate a unimolecular decomposition and are consistent with a proposed stepwise mechanism involving cyclization of the nitrosimine followed by loss of N(2). The ground-state conformations of the parent nitrosiminothiazoline (9a) and transition states for rotation around the exocyclic C==N bond, electrocyclic ring closure, and loss of N(2) were calculated using ab initio molecular orbital theory at the MP2/6-31G* level. The calculated gas-phase barrier height for the loss of N(2) from 9a (25.2 kcal/mol, MP4(SDQ, FC)/6-31G*//MP2/6-31G* + ZPE) compares favorably with the experimental barrier for 2a of 25.3 kcal/mol in cyclohexane. The potential energy surface is unusual; the rotational transition state 9a-rot-ts connects directly to the orthogonal transition state for ring-closure 9aTS. The decoupling of rotational and pseudopericyclic bond-forming transition states is contrasted with the single pericyclic transition state (15TS) for the electrocyclic ring-opening of oxetene (15) to acrolein (16). For comparison, the calculated homolytic strength of the N--NO bond is 40.0 kcal/mol (MP4(SDQ, FC)/6-31G*//MP2/6-31G* + ZPE).

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Section: Methodssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%

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Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines¹

et al. 2001

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“…The contribution of resonance form 4a was shown by means of electron spectroscopy for chemical analysis (ESCA in other words XPS) and 1 H NMR spectra by comparison with the corresponding data of related compounds 11. Photolysis of 4 afforded the diphenyl disulfide derivative 6 as the main product through π–π* excitation 12. Disulfide 6 is a dimerization product of a thiyl radical C , generated by ring opening of 4 .…”

Section: Phosphoranes and Nitrosoiminesmentioning

confidence: 99%

Studies on hypervalent compounds and synthetic work using heteroaromatic cations

Akiba¹

2011

Heteroatom Chemistry

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Studies on low‐coordinated nitrogen, phosphorus, sulfur, and selenium compounds

Inamoto¹

2001

Heteroatom Chemistry

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The major studies of my laboratory on heteroatom chemistry are briefly outlined and include the following topics: (1) novel radical reactions to kinetic stabilization of organosulfur and selenium compounds, (2) novel reactions of organophosphorus compounds, (3) reaction of the S atom to stabilization of o-thioquinonemethides, (4) N-nitrosoimines stabilized by heterocycles to hypervalent sulfur compounds, and (5) phosphinidenes (R-P) to kinetic stabilization of low-coordinated organophosphorus compounds.

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Formation of bis[-(N-substituted cyanamino)phenyl] disulfides by photolysis of 3-substituted 2-nitrosoimino-2, 3-dihydrobenzothiazoles

Cited by 4 publications

References 2 publications

Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines¹

Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines¹

Studies on hypervalent compounds and synthetic work using heteroaromatic cations

Studies on low‐coordinated nitrogen, phosphorus, sulfur, and selenium compounds

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Formation of bis[-(N-substituted cyanamino)phenyl] disulfides by photolysis of 3-substituted 2-nitrosoimino-2, 3-dihydrobenzothiazoles

Cited by 4 publications

References 2 publications

Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines1

Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines1

Studies on hypervalent compounds and synthetic work using heteroaromatic cations

Studies on low‐coordinated nitrogen, phosphorus, sulfur, and selenium compounds

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Resources

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Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines¹

Experimental and Theoretical Studies on the Thermal Decomposition of Heterocyclic Nitrosimines¹