The chemistry of bisallenes

Hopf, Henning; Μαρκόπουλος, Γεώργιος

doi:10.3762/bjoc.8.225

Cited by 24 publications

(21 citation statements)

References 290 publications

(325 reference statements)

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“…Taken together, these studies show that conjugated bisallenes [39], which are readily available by high-yielding synthetic transformations from simple substrates, are useful starting materials for the preparation of a plethora of novel organic compounds.…”

Section: Resultsmentioning

confidence: 99%

Polar reactions of acyclic conjugated bisallenes

Stamm¹,

Hopf²

2013

Beilstein J. Org. Chem.

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SummaryThe chemical behaviour of various alkyl-substituted, acyclic conjugated bisallenes in reactions involving polar intermediates and/or transition states has been investigated on a broad scale for the first time. The reactions studied include lithiation, reaction of the thus formed organolithium salts with various electrophiles (among others, allyl bromide, DMF and acetone), oxidation to cyclopentenones and epoxides, hydrohalogenation (HCl, HBr addition), halogenation (Br2 and I2 addition), and [2 + 2] cycloaddition with chlorosulfonyl isocyanate. The resulting adducts were fully characterized by spectroscopic and analytical methods; they constitute interesting substrates for further organic transformations.

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Section: Resultsmentioning

confidence: 99%

Polar reactions of acyclic conjugated bisallenes

Stamm¹,

Hopf²

2013

Beilstein J. Org. Chem.

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“…25,55 Although no X-ray analysis of 6 has been reported (the compound is a liquid at room temperature), X-ray structural analyses of about 4 dozen solid derivatives of 6 have been reported in the Cambridge Crystallographic Database. 16 Turning to Diels-Alder cycloadditions now, while we have been unable to locate a publication describing the experimental or computed conformational dynamics of the molecule, it is clear that 6 has no difficulties acquiring the cisoid conformation required for the reaction to take place. As mentioned earlier, calculations point to a faster and more thermodynamically favorable Diels-Alder reaction with 6 as a diene than with vinylallene 4.…”

Section: Special Topic Synthesis 22 Bisallenesmentioning

confidence: 97%

Allenes in Diels–Alder Cycloadditions

Hopf

Sherburn

2021

Synthesis

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For a long time, allenes—and cumulenic systems in general—played a relatively minor role in Diels–Alder cycloadditions. This situation has changed, since allenes are more readily available and as their unique stereochemical features in [4+2]cycloadditions are more widely recognized. This review presents a comprehensive overview of allenes in Diels–Alder processes using selected examples. Allenes in dienes, dienophiles and cycloadducts are covered, inter- and intramolecular Diels–Alder cycloadditions are discussed, and stereochemical features of the addition process are described. Areas of emerging importance are also covered, including allenic components in dehydro-Diels–Alder processes, and dendralenic allenes in Diels–Alder sequences for the rapid generation of target-relevant molecular complexity. Preparatively useful methods for allenic precursor synthesis are also discussed.1 Introduction2 Allenic Dienes2.1 Vinylallenes2.2 Bisallenes2.3 Cross-conjugated Allenes3 Allenic Dienophiles4 Intramolecular Diels–Alder Cycloadditions5 Allenic Cycloadducts6 Conclusions and Outlook

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“…Cycloallenes are synthetically interesting compounds that, given their reduced symmetry due to the ring structure, exhibit helical MOs. 29,30,[71][72][73][74][75] Most recently, Ramirez et al 30 demonstrated that secondary orbital interactions due to the helical frontier MO topology are responsible for the endo selectivity in Diels-Alder reactions. Four molecular structures of simple cycloallenes are shown in the top of Figure 7, from left to right, 1,2cyclohexadiene, 1,2-cycloheptadiene, 1,2-cyclooctadiene and 1,2-cyclononadiene.…”

Section: Cycloallenesmentioning

confidence: 99%

Quantification of the Helicality of Helical Molecular Orbitals

Bro-Jørgensen

Garner

Solomon

2021

Preprint

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The frontier molecular orbital (MO) topology of linear carbon molecules, such as polyynes, can be visually identified as helices. However, there is no clear way to quantify the helical curvature of these ⇡-MOs and it is thus challenging to quantify correlations between the helical curvature and molecular properties. In this paper, we develop a method that enables us to compute the helical curvature of MOs based on their nodal planes. Using this method, we define a robust way of quantifying the helical nature of MOs (helicality) by their deviation from a perfect helix. We explore several limiting cases, including polyynes, metallacumulenes, cyclic allenes, and spiroconjugated systems where the change in helical curvature is subtle, yet clearly highlighted with this method. For example, we show that strain only has a minor effect on the helicality of the frontier orbitals of cycloallenes and that the MOs of spiroconjugated systems are close to perfect helices around the spiro-carbon. Our work provides a well-defined method for assessing orbital helicality beyond visual inspection of MO isosurfaces, thus paving the way for future studies of how the helicality of ⇡-MOs affects molecular properties.

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The chemistry of bisallenes

Cited by 24 publications

References 290 publications

Polar reactions of acyclic conjugated bisallenes

Polar reactions of acyclic conjugated bisallenes

Allenes in Diels–Alder Cycloadditions

Quantification of the Helicality of Helical Molecular Orbitals

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