A relative approach for determining ring strain energies of heterobicyclic alkenes

Howell, Jennifer; Goddard, John D.; Tam, William

doi:10.1016/j.tet.2009.03.090

Cited by 35 publications

(31 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, the SE of norbornane obtained by the homodesmotic method (63.15 kJ·mol -1 ) [57] is in agreement with experimental value (60.22 kJ·mol -1 ) [58]. In the present work, the SE of NNNAHP and CL-20 were calculated using the designed homodesmotic reactions (1) and (2).…”

Section: Strain Energysupporting

confidence: 85%

Crystal structure, detonation performance, and thermal stability of a new polynitro cage compound: 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptacyclo [5.5.1.13, 11. 15, 9] pentadecane

Zhang

Wang

et al. 2011

J Mol Model

View full text Add to dashboard Cite

A new polynitro cage compound 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptcyclo [5.5.1.1(3,11).1(5,9)] pentadecane (NNNAHP) was designed in the present work. Its molecular structure was optimized at the B3LYP/6-31 G(d,p) level of density functional theory (DFT) and crystal structure was predicted using the Compass and Dreiding force fields and refined by DFT GGA-RPBE method. The obtained crystal structure of NNNAHP belongs to the P-1 space group and the lattice parameters are a = 9.99 Å, b = 10.78 Å, c = 9.99 Å, α = 90.01°, β = 120.01°, γ = 90.00°, and Z = 2, respectively. Based on the optimized crystal structure, the band gap, density of state, thermodynamic properties, infrared spectrum, strain energy, detonation characteristics, and thermal stability were predicted. Calculation results show that NNNAHP has detonation properties close to those of CL-20 and is a high energy density compound with moderate stability.

show abstract

Section: Strain Energysupporting

confidence: 85%

Crystal structure, detonation performance, and thermal stability of a new polynitro cage compound: 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptacyclo [5.5.1.13, 11. 15, 9] pentadecane

Zhang

Wang

et al. 2011

J Mol Model

View full text Add to dashboard Cite

show abstract

“…The directing angle of the corner unit was rendered obtuse, for the first time, with a bicyclic structure, which increased the number of participating units in the one‐pot macrocyclization reaction. We believe that bicyclic systems with preinstalled ring strain may be of interest for further exploration of uniquely accessible nanohoop congeners . Crystallographic analyses of the macrocyclic intermediates revealed important roles of the directing angle as well as the three‐dimensional cyclic structure in determining the number of participating units.…”

Section: Discussionmentioning

confidence: 97%

An Obtuse‐angled Corner Unit for Fluctuating Carbon Nanohoops

Sun

Miyamoto

Sato

et al. 2016

Chemistry An Asian Journal

View full text Add to dashboard Cite

The invention of corner units was the key factor that allowed the synthesis of cyclo-para-phenylenes with strained curved π-systems. Despite only a few scarce instances of the development of corner units to date, a variety of structural congeners have been synthesized. These preceding corner units commonly possessed directing angles of ≤90°, which enabled the macrocyclization of multiple units, up to six. In this study, we introduce an obtuse-angled corner unit for the synthesis of cyclo-para-phenylene congeners. The corner unit with oxanorbornadiene possessed a directing angle of 126° and thus allowed for the macrocyclization of larger structures with up to seven units. Reductive aromatization was applicable to complete the cyclo-para-phenylene structures and afforded the congeners with multiple anthracenylene panels. Structural studies with experimental and theoretical methods revealed a fluctuating structure with an intrinsic non-belt shape.

show abstract

“…21 4-Benzyloxybutyraldehyde Dimethyl Acetal (11). To a solution of 4-benzyloxy-1-butane (0.507 g, 2.81 mmol) in CH 2 Cl 2 (14 mL) were added 3 Å molecular sieves (1.41 g), silica (1.33 g), and pyridinium chlorochromate (1.22 g, 5.66 mmol).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Furthermore, such close interaction would be disfavored because it would approximate the formation of a 2,7-dioxabicyclo[2.2.1]heptane structure (3b, eq 1), effectively destabilizing this onium ion by up to 15 kcal/mol. 11 In this Article, we provide evidence that alkoxy groups, which are generally considered to be nonparticipating with respect to stereochemistry, 12−20 can accelerate the ionization of acetals. Preliminary studies suggested that the influence of alkoxy groups on the rates of ionization of acetals (up to 20-fold acceleration compared to that for substrates without alkoxy groups) occurs by electrostatic stabilization of an oxocarbenium ion intermediate, not neighboring-group participation through covalently bonded intermediates.…”

Section: ■ Introductionmentioning

confidence: 99%

Influence of Alkoxy Groups on Rates of Acetal Hydrolysis and Tosylate Solvolysis: Electrostatic Stabilization of Developing Oxocarbenium Ion Intermediates and Neighboring-Group Participation To Form Oxonium Ions

et al. 2015

View full text Add to dashboard Cite

The hydrolysis of 4-alkoxy-substituted acetals was accelerated by about 20-fold compared to that of sterically comparable substrates that do not have an alkoxy group. Rate accelerations are largest when the two functional groups are linked by a flexible cyclic tether. When controlled for the inductive destabilization, an alkoxy group can accelerate acetal hydrolysis by up to 200-fold. The difference in rates of acetal hydrolysis between a substrate where the alkoxy group was tethered to the acetal group by a five-membered ring compared to one where it was tethered by an eight-membered ring was less than 100-fold, suggesting that fused-ring intermediates were not formed. By comparison, the difference in rates of solvolysis of structurally related tosylates were nearly 10(6)-fold between the five- and eight-membered ring series. This observation implicates neighboring-group participation in the solvolysis of tosylates but not in the hydrolysis of acetals. The acceleration of acetal hydrolysis by an alkoxy group is better explained by electrostatic stabilization of intermediates that accumulate positive charge at the acetal carbon atom.

show abstract

A relative approach for determining ring strain energies of heterobicyclic alkenes

Cited by 35 publications

References 43 publications

Crystal structure, detonation performance, and thermal stability of a new polynitro cage compound: 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptacyclo [5.5.1.13, 11. 15, 9] pentadecane

Crystal structure, detonation performance, and thermal stability of a new polynitro cage compound: 2, 4, 6, 8, 10, 12, 13, 14, 15-nonanitro-2, 4, 6, 8, 10, 12, 13, 14, 15-nonaazaheptacyclo [5.5.1.13, 11. 15, 9] pentadecane

An Obtuse‐angled Corner Unit for Fluctuating Carbon Nanohoops

Influence of Alkoxy Groups on Rates of Acetal Hydrolysis and Tosylate Solvolysis: Electrostatic Stabilization of Developing Oxocarbenium Ion Intermediates and Neighboring-Group Participation To Form Oxonium Ions

Contact Info

Product

Resources

About