The antiaromaticity of cyclobutadiene

Herr, M.L.

doi:10.1016/0040-4020(76)80132-9

Cited by 4 publications

(1 citation statement)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Herr noted that formation of 8a should be much easier than 8b from the corresponding dihydroquinones due to the extra resonance stabilization in 8a . While the isomer 8a is unknown, the synthesis of isomer 8b , 32.3 kcal/mol higher in energy, has been attempted .…”

Section: Generalmentioning

confidence: 99%

Computational Studies of Cyclobutadiene and Benzocyclobutene Fused to p- and o-Quinone

et al. 1998

View full text Add to dashboard Cite

Cyclobutadiene and benzocyclobutenes fused to o- and p-quinone have been studied by computational methods. Geometries were optimized at the B3LYP/6-31G* level, and absolute NMR shielding values were calculated using the GIAO method with the HF/6-31G* basis set. NICS values of the compounds 8b,c and 9b,c indicate strong antiaromatic character for cyclobutadiene units. However, 8a and 9a show negative NICS values where the quinodal system reduces the antiaromaticity significantly by forcing these systems to possess a dimethylene-like structure. The calculated 13C NMR chemical shifts of 6 − 9 and parent systems are in very good agreement with literature values.

show abstract

Section: Generalmentioning

confidence: 99%

Computational Studies of Cyclobutadiene and Benzocyclobutene Fused to p- and o-Quinone

et al. 1998

View full text Add to dashboard Cite

show abstract

Emerging Chemodiversity and Stereoisomerism in Acyclic Mono‐ and Dichloroalkanes

Testa

2018

Chemistry & Biodiversity

View full text Add to dashboard Cite

The objective of this pen-and-paper study is to monitor the growth of structural complexity as a function of the number of heavy atoms. This is done here using simple chloroalkanes, the indices of structural complexity being the number of regioisomers and mainly stereoisomeric features. Following a previous work dealing with acyclic alkanes, the present study focuses on all acyclic monochloroalkanes from four heavy atoms (four regioisomers) to 10 heavy atoms (2 to 211 regioisomers, respectively). Similarly, all acyclic dichloroalkanes were drawn, ranging from five heavy atoms to nine heavy atoms (4 to 130 regioisomers, respectively). The first part of the work describes the nature and number of stereoisomeric features seen to emerge in molecular structures featuring one or more stereogenic centers. These molecular features include enantiomerism, diastereoisomerism, pseudoasymmetry, and meso-isomerism. The first appearance of chirality among the monochloro and dichloro homologs occurred in the families with five heavy atoms. Diastereoisomerism, meso-isomerism, and pseudoasymmetry appear in higher families of homologs. The second part of the article is an attempt to rationalize the appearance of regioisomers, stereogenic centers, and stereoisomers as their number grows along homologous series, from one family of regioisomers to the higher ones. Far from being random as anticipated, such increases appear regular and ordered. Indeed, the data available demonstrate exponential increases and suggest the involvement of geometric order in the growth of chemical complexity.

show abstract

Structure of anti-aromatic molecules. VI. The multipicity of solutions and the problem of artefact structures. Annuleno-annulenes

Simkin¹,

Glukhovtsev²

1983

J Struct Chem

View full text Add to dashboard Cite

The antiaromaticity of cyclobutadiene

Cited by 4 publications

References 16 publications

Computational Studies of Cyclobutadiene and Benzocyclobutene Fused to p- and o-Quinone

Computational Studies of Cyclobutadiene and Benzocyclobutene Fused to p- and o-Quinone

Emerging Chemodiversity and Stereoisomerism in Acyclic Mono‐ and Dichloroalkanes

Structure of anti-aromatic molecules. VI. The multipicity of solutions and the problem of artefact structures. Annuleno-annulenes

Contact Info

Product

Resources

About