Iminopropadienones from Dioxanediones, Isoxazolopyrimidinones, Pyridopyrimidinones, and Pyridopyrimidinium Olates

Shtaiwi, Majed; Wentrup, Curt

doi:10.1021/jo026275+

Cited by 21 publications

(13 citation statements)

References 11 publications

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“…[1][2][3][4] These unusual cumulenes have been characterized by IR and NMR spectroscopy [1][2][3][4][5] as well as by their chemical reactions. Iminopropadienones 4 undergo a multitude of nucleophilic addition reactions; with bisnucleophiles, cyclization leads to a variety of heterocyclic compounds containing 5-, 6-, 7-, 8-, and 9-membered rings.…”

Section: Introductionmentioning

confidence: 99%

“…2,4,6 Thus, in particular, the 2-pyridyl-and 2,6-difluorophenyliminopropadienones afford significant amounts of "abnormal" products apparently arising from initial attack of the strongest nucleophilic center of the bisnucleophile on the CdN group, or from attack of the weaker nucleophilic center on the CdO group. 2,4,6 The addition of tertiary and secondary amines to aryliminopropadienones has been examined by low temperature IR spectroscopy. 7 Tertiary amines (trimethylamine) add to the CdO group to form ketenimine-type zwitterionic intermediates in all cases.…”

Section: Introductionmentioning

confidence: 99%

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Reaction of Iminopropadienones with Amines: Mechanistic Explanations of Zwitterionic Intermediate, Ketene and Ketenimine Formation

et al. 2008

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The complex reaction of thermally generated iminopropadienones with amines in the gas phase and upon matrix deposition and its varying product composition is investigated using density functional theory. In the high energy gas phase addition a single amine molecule reacts readily with iminopropadienone with the decisive step being a 1,3-hydrogen shift and activation barriers of at least 100 kJ/mol. In accordance with the experiment, the formation of ketenes is favored. In the condensed phase of an amine matrix, the utilization of amine dimers both as reagents and as explicit solvents lowers the activation energy required to a feasible 20-30 kJ/mol and predicts ketenimines as the main products, as observed experimentally.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reaction of Iminopropadienones with Amines: Mechanistic Explanations of Zwitterionic Intermediate, Ketene and Ketenimine Formation

et al. 2008

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“…However, some iminopropadienones are isolable at room temperature, and this has allowed the recording of 13 C NMR spectra in several cases . They are mostly generated by flash vacuum thermolysis (FVT) from precursors such as 1,3-dioxane-4,6-diones (Meldrum’s acid derivatives) and isoxazolopyrimidinone derivatives. − We have investigated the reactivity of the iminopropadienones with different amines, viz. DMA, diethylamine (DEA), and TMA.…”

Section: Introductionmentioning

confidence: 99%

Reaction of Iminopropadienones with Amines—Formation of Zwitterionic Intermediates, Ketenes, and Ketenimines

et al. 2008

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Five aryliminopropadienones 4a- d have been synthesized by flash vacuum thermolysis (FVT) by using two different precursors in each case. These compounds were deposited at 50 K at a pressure of ca. 10(-6) mbar together with three different nucleophiles, namely, trimethylamine (TMA), dimethylamine (DMA), and diethylamine (DEA), in order to study their reactions as neat solids during warm-up by FTIR spectroscopy. The reaction with TMA showed that a zwitterionic species (5 and/or 6) was formed in all the cases. With DMA and DEA, an alpha-oxoketenimine and/or an imidoylketene (7 and 8 or 9 and 10) was formed as the final product. In addition, several bands were observed, which can be assigned to zwitterionic intermediates (11 or 12). Optimized structures and vibrational spectra for all products were calculated at the B3LYP/6-31G(d) level of theory by using the polarizable continuum model (epsilon = 5).

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“…Therefore, in this series, species 3 [R = N−C(NH)NH 2 ] is predicted to be the most flexible molecule in the OCCCN plane and suggests its high tendency to cyclization. Other works have shown the electrophilic character of the CO group of iminopropadienones reacting with amines − and alcohol . In particular, Aly and Nour-El-Din pointed out that cyclization is a very important reaction of amidines, leading to various heterocyclic compounds, including pyrimidines …”

Section: Resultsmentioning

confidence: 99%

A New Mechanism of Guanine-Isomer Formation from Species Previously Observed in the Interstellar Medium

Silva

Araujo

2017

ACS Earth Space Chem.

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Adenine and guanine have been observed in meteor material. Because of this, they are thought to have been formed in the interstellar medium. However, while there exist several theoretical works exploring the mechanisms of formation for adenine, guanine has received only minor attention. In this work, a retrosynthetic analysis strategy was employed to suggest a new mechanism of guanine formation from species previously observed in the interstellar medium: HCN, CCO, HNCNH, and its isomer H 2 NCN. MP2/6-311++G(2d,2p) calculations were used to evaluate the Gibbs free energy of the minimum and transition states involved in a simple reaction mechanism, involving only five steps. The intermediate species are highly polar (dipole moment range of 4.35−7.72 D), which make them candidates for observation in the rotational spectra. In terms of energy, this new mechanism is very exergonic, and the energy barriers are monotonically decreasing. The value of the energy barrier for the first step in this mechanism was substantially reduced when water molecules were explicitly introduced as a way to represent water-ice-coated grain surfaces.

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Iminopropadienones from Dioxanediones, Isoxazolopyrimidinones, Pyridopyrimidinones, and Pyridopyrimidinium Olates

Cited by 21 publications

References 11 publications

Reaction of Iminopropadienones with Amines: Mechanistic Explanations of Zwitterionic Intermediate, Ketene and Ketenimine Formation

Reaction of Iminopropadienones with Amines: Mechanistic Explanations of Zwitterionic Intermediate, Ketene and Ketenimine Formation

Reaction of Iminopropadienones with Amines—Formation of Zwitterionic Intermediates, Ketenes, and Ketenimines

A New Mechanism of Guanine-Isomer Formation from Species Previously Observed in the Interstellar Medium

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