Matrix Photochemistry at Low Temperatures and Spectroscopic Properties of γ-Butyrothiolactone

Dugarte, Nahir; Erben, Mauricio F.; Romano, Rosana M.; Ge, Maofa; Yao, Li; Védova, Carlos O. Della

doi:10.1021/jp105767y

Cited by 18 publications

(28 citation statements)

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“…Several reports have pointed out that the strain energies of cyclic molecules are influenced by heteroatom substitution or functionalization. 32 − 35 Thus, our results are comparable to these reports. The influence of substitution with the halogen atoms is quite minimal when compared to the heteroatom effect on the CHP ring.…”

Section: Results and Discussionsupporting

confidence: 92%

“…Most theoretical methods often require the computation of the total energies of the molecule of interest relative to an acyclic strain-free counterpart. The strain energies of the studied systems have been computed at the MP2/aug-cc-pVTZ and the M06-2X/6-311++G(d,p) level of theory in line with refs ( 21 , 32 ). This approach involves the computation of the ring strain energy relative to the strain energy of the six-membered counterparts, which several studies had reported to be less strained among the cycloalkane family.…”

Section: Results and Discussionmentioning

confidence: 99%

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Meta-Hybrid Density Functional Theory Prediction of the Reactivity, Stability, and IGM of Azepane, Oxepane, Thiepane, and Halogenated Cycloheptane

et al. 2022

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The application of plain cycloalkanes and heterocyclic derivatives in the synthesis of valuable natural products and pharmacologically active intermediates has increased tremendously in recent times with much attention being paid to the lower cycloalkane members. The structural and molecular properties of higher seven-membered and nonaromatic heterocyclic derivatives are less known despite their stable nature and vast application; thus, an insight into their structural and electronic properties is still needed. Appropriate quantum chemical calculations utilizing the ab initio (MP2) method, meta-hybrid (M06-2X) functional, and long-range-separated functionals (ωB97XD) have been utilized in this work to investigate the structural reactivity, stability, and behavior of substituents on cycloheptane (CHP) and its derivatives: azepane, oxepane, thiepane, fluorocycloheptane (FCHP), bromocycloheptane (BrCHP), and chlorocycloheptane (ClCHP). Molecular global reactivity descriptors such as Fukui function, frontier molecular orbitals (FMOs), and molecular electrostatic potential were computed and compared with lower members. The results of two population methods CHELPG and Atomic Dipole Corrected Hirshfeld Charges (ADCH) were equally compared to scrutinize the charge distribution in the molecules. The susceptibility of intramolecular interactions between the substituents and cycloalkane ring is revealed by natural bond orbital analysis and intramolecular weak interactions by the independent gradient model (IGM). Other properties such as atomic density of states, intrinsic bond strength index (IBSI), and dipole moments are considered. It is acclaimed that the strain effect is a major determinant effect in the energy balance of cyclic molecules; thus, the ring strain energies and validation of spectroscopic specificities with reference to the X-ray crystallographic data are also considered.

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Section: Results and Discussionsupporting

confidence: 92%

Section: Results and Discussionmentioning

confidence: 99%

Meta-Hybrid Density Functional Theory Prediction of the Reactivity, Stability, and IGM of Azepane, Oxepane, Thiepane, and Halogenated Cycloheptane

et al. 2022

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“…Regarding cyclic thioesters, i.e., thiolactones, small and medium-sized thiolactones (4 < n < 7), such as β-propiolactone (n = 4), 153 γ-butyrothiolactone (n = 5), 154 and δvalerothiolactone (n = 6) 155 are constrained in the less favorable anti conformation (Figure 9). Computational analysis suggests that this is also the case for ε-caprothiolactone (n = 7).…”

Section: Peptide Thioesters and Peptide Selenoesters: General Propert...mentioning

confidence: 99%

Native Chemical Ligation and Extended Methods: Mechanisms, Catalysis, Scope, and Limitations

et al. 2019

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The native chemical ligation reaction (NCL) involves reacting a C-terminal peptide thioester with an N-terminal cysteinyl peptide to produce a native peptide bond between the two fragments. This reaction has considerably extended the size of polypeptides and proteins that can be produced by total synthesis and has also numerous applications in bioconjugation, polymer synthesis, material science, and micro-and nanotechnology research. The aim of the present review is to provide a thorough mechanistic overview of NCL and extended methods. The most relevant properties of peptide thioesters, Cys peptides, and common solvents, reagents, additives, and catalysts used for these ligations are presented. Mechanisms, selectivity and reactivity are, whenever possible, discussed through the insights of computational and physical chemistry studies. The inherent limitations of NCL are discussed with insights from the mechanistic standpoint. This review also presents a palette of O,S-, N,S-, or N,Se-acyl shift systems as thioester or selenoester surrogates and discusses the special molecular features that govern reactivity in each case. Finally, the various thiol-based auxiliaries and thiol or selenol amino acid surrogates that have been developed so far are discussed with a special focus on the mechanism of long-range N,S-acyl migrations and selective dechalcogenation reactions.

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“…Ethylketene is evidenced by bands in the FTIR spectrum at 1141 cm −1 (Figure 3), 2135 cm −1 , and 2130 cm −1 (Figure 2), matching bands observed for matrix-isolated ethylketene in the literature. 25 There is also a tiny feature at m/z = 70 (CH 3 CH 2 CH=C=O + ) observable in the mass spectrum following 1000 K pyrolysis. The coproduct of elimination, H 2 (IE = 15.4 eV), 18 cannot be observed in the mass spectra.…”

Section: B Products Of Eliminationmentioning

confidence: 99%

Thermal decomposition products of butyraldehyde

Hatten

Kaskey

Warner

et al. 2013

The Journal of Chemical Physics

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The thermal decomposition of gas-phase butyraldehyde, CH3CH2CH2CHO, was studied in the 1300-1600 K range with a hyperthermal nozzle. Products were identified via matrix-isolation Fourier transform infrared spectroscopy and photoionization mass spectrometry in separate experiments. There are at least six major initial reactions contributing to the decomposition of butyraldehyde: a radical decomposition channel leading to propyl radical + CO + H; molecular elimination to form H2 + ethylketene; a keto-enol tautomerism followed by elimination of H2O producing 1-butyne; an intramolecular hydrogen shift and elimination producing vinyl alcohol and ethylene, a β-C-C bond scission yielding ethyl and vinoxy radicals; and a γ-C-C bond scission yielding methyl and CH2CH2CHO radicals. The first three reactions are analogous to those observed in the thermal decomposition of acetaldehyde, but the latter three reactions are made possible by the longer alkyl chain structure of butyraldehyde. The products identified following thermal decomposition of butyraldehyde are CO, HCO, CH3CH2CH2, CH3CH2CH=C=O, H2O, CH3CH2C≡CH, CH2CH2, CH2=CHOH, CH2CHO, CH3, HC≡CH, CH2CCH, CH3C≡CH, CH3CH=CH2, H2C=C=O, CH3CH2CH3, CH2=CHCHO, C4H2, C4H4, and C4H8. The first ten products listed are direct products of the six reactions listed above. The remaining products can be attributed to further decomposition reactions or bimolecular reactions in the nozzle.

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Matrix Photochemistry at Low Temperatures and Spectroscopic Properties of γ-Butyrothiolactone

Abstract: The five-membered heterocyclic gamma-butyrothiolactone was isolated in a low-temperature, inert Ar matrix, and the UV-visible (200 Show more

Cited by 18 publications

References 50 publications

Meta-Hybrid Density Functional Theory Prediction of the Reactivity, Stability, and IGM of Azepane, Oxepane, Thiepane, and Halogenated Cycloheptane

Meta-Hybrid Density Functional Theory Prediction of the Reactivity, Stability, and IGM of Azepane, Oxepane, Thiepane, and Halogenated Cycloheptane

Native Chemical Ligation and Extended Methods: Mechanisms, Catalysis, Scope, and Limitations

Thermal decomposition products of butyraldehyde

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