Dendralenes Branch Out: Cross‐Conjugated Oligoenes Allow the Rapid Generation of Molecular Complexity

Hopf, Henning; Sherburn, Michael S.

doi:10.1002/anie.201102987

Cited by 155 publications

(133 citation statements)

References 396 publications

(650 reference statements)

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“…[174] The authors' group has pioneered the synthesis and exploration of the reactivity of a fundamental class of unsaturated hydrocarbons, the dendralenes. [175] As polyalkenes, dendralenes are prime substrates for multi-bond forming processes. The ivyanes, polycyclic helically chiral molecules that exhibit extraordinarily high heats of combustion, are generated in one step from dendralenes by exhaustive cyclopropanation sequences.…”

Section: Independent Reactionsmentioning

confidence: 99%

Multi-Bond Forming Processes in Efficient Synthesis

Green¹,

Sherburn²

2013

Aust. J. Chem.

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An increasing number of synthetic organic chemists are embracing the philosophy of efficiency. Herein we highlight multi-bond forming processes, which form two or more new covalent bonds in a single synthetic operation. Such processes, which have the ability to rapidly increase structural complexity, are preeminent in contemporary synthetic organic chemistry. In this short review we classify, analyse, and contrast contemporary multi-bond forming processes, frame these cutting edge contributions within a historical context, and speculate on likely future developments in the area.

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Section: Independent Reactionsmentioning

confidence: 99%

Multi-Bond Forming Processes in Efficient Synthesis

Green¹,

Sherburn²

2013

Aust. J. Chem.

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“…[1,2] As this molecule comprises multi ple 2substituted or 2,3disubstituted1,3dienyl frameworks, den dralene has been attracting considerable attention because of its unique chemical reactivity, especially as a substrate for the diene transmissive Diels-Alder reaction. [3,4] Until the synthesis of den dralenes via crosscoupling reactions was reported, a majority of the dendralenes were prepared by the thermal decomposition of precursors.…”

Section: Introductionmentioning

confidence: 99%

Anionic Polymerization of 2‐Hexyl[3]dendralene

Takamura

Takenaka

Toda

et al. 2017

Macro Chemistry & Physics

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studies have reported the addition poly merization of [3]dendralene derivatives. [10] Previously, our group has reported the anionic polymerization of 2phenyl [3]den dralene (P3D) and 2(4methoxyphenyl) [3]dendralene (MP3D). [11] In both cases, anionic polymerization smoothly pro ceeds in polar solvents at low tempera ture, affording a polymer with a narrow mole cular weight distribution and a conjugate addition chain structure com prising conjugated carbon-carbon double bonds in the polymer chain, as shown in Scheme 1. However, a bimodal molecular weight distribution was observed when the poly merization mixture was stand still for a long duration after the monomer was completely consumed, presumably because of the nucleophilic addition of the propagating carbanion to the conjugated double bond in the polymer chain, as shown in Scheme 2. Hence, it is crucial to select the polymerization conditions to obtain polymers with controlled chain structures.This side reactions, nucleophilic addition of propagating chain end to the polymer chain, can also be prevented via the lowering of the reactivity of conjugated carbon-carbon double bond in the polymer chain by changing the double bond sub stituent. The carbon-carbon double bond in the polymer chain is conjugated by the phenyl group (Scheme 2), which facilitates easier nucleophilic attack of the propagating carbanion to the double bond compared with the case of an unsubstituted double bond. Hence, the polymerization behavior of [3]den dralene derivatives with a nonconjugating substituent on the C2 carbon of the [3]dendralene framework is interesting. Hence, 2(nhexyl)[3]dendralene (H3D) is selected as a candi date to compare the effect of substituents on its polymerization behavior with that of P3D.Notably, the microstructure of the resulting polymers is also interesting. As expected, the 2substituted[3]dendralene Dendralene In this study, the polymerization behavior of 2-hexyl[3]dendralene (H3D), which is an alkyl-group-derived [3]dendralene, is examined. The polymerization of H3D in tetrahydrofuran (THF) at −78 °C with potassium naphthalenide as the initiator affords poly(H3D) with a narrow molecular weight distribution, although a small shoulder peak is observed at a high molecular weight even before the monomer is completely consumed. The molecular weight distribution of poly(H3D) prepared in heptane is broader than that prepared in THF, indicating that the nucleophilic addition of a propagating carbanion to the carbon-carbon double bond in the polymer chain occurs in addition to polymerization. Furthermore, the microstructure of poly(H3D) is investigated by NMR. Signals corresponding to the conjugate addition structure, that is, 1,4-and 4,6-structures, are exclusively observed. Poly(H3D) prepared in heptane contains a higher content of the 4,6-structures compared with those prepared in THF.

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“…[4][5][6][7][8] Despite almost a century of research, [9] the DA reaction remains a highly active area of study, and current fields of interest include the development of new catalytic asymmetric reactions, [10] incorporation of DA reactions into domino sequences, [11,12] the elucidation of natural product biosyntheses, [13][14][15][16][17] and the development of diene-transmissive DA reactions. [18][19][20][21][22] Although the DA reaction has been used to access a vast array of structural motifs, the reaction is not without limitation.…”

Section: Introductionmentioning

confidence: 99%