Abstract:A general synthetic approach to molecular structures that are hybrids of tetraethynylethylene (TEE) and tetravinylethylene (TVE) is reported. The synthesis permits the controlled preparation of many previously inaccessible structures, including examples with different substituents on each of the four branching arms. Most substituted TVE−TEE hybrids are found to be significantly more robust compounds than their unsubstituted counterparts, enhancing the prospects of their deployment in conducting materials and d… Show more
“…Cross-conjugated polyenes have significant potential in functional materials, but, thus far, these compounds have mainly been used in step-economic synthesis. Specifically, substituted [3]dendralenes have been exploited as multidienes in “diene-transmissive” Diels–Alder sequences leading to natural products .…”
Section: Resultsmentioning
confidence: 99%
“…The route involves twofold Negishi cross-couplings of 1,1-dibromoalkenes . We have since extended these investigations to the stereoselective preparation of tetravinylethylene/tetraethynylethylene hybrids . In stark contrast to the extensive work on [3]dendralenes, surprisingly few [4]dendralenes have been prepared, and no general synthesis exists. ,,, The present article addresses this deficiency and demonstrates how substitution can control the powerful Diels–Alder reactivity of [4]dendralene …”
The first general synthesis of branched tetraenes ([4]dendralenes)
involves two or three steps from inexpensive, commodity chemicals.
It involves an unprecedented variation on Suzuki–Miyaura cross-coupling,
generating two new C–C bonds in a one-flask operation with
control of diastereoselectivity. The broad scope of the method is
established through the synthesis of more than 60 diversely substituted
[4]dendralene molecules, along with substituted buta-1,3-dienes and
other [n]dendralenes. [4]Dendralenes are demonstrated
to be significantly more kinetically stable than their well-known
[3]dendralene counterparts. The first stereoselective synthesis of
these compounds is also reported, through the catalyst-controlled
generation of both E- and Z-diastereomeric
products from the same precursor. Novel, through-conjugated/cross-conjugated
hybrid molecules are introduced. The first selective dienophile cycloadditions
to substituted [4]dendralenes are reported, thus paving the way for
applications in target-oriented synthesis.
“…Cross-conjugated polyenes have significant potential in functional materials, but, thus far, these compounds have mainly been used in step-economic synthesis. Specifically, substituted [3]dendralenes have been exploited as multidienes in “diene-transmissive” Diels–Alder sequences leading to natural products .…”
Section: Resultsmentioning
confidence: 99%
“…The route involves twofold Negishi cross-couplings of 1,1-dibromoalkenes . We have since extended these investigations to the stereoselective preparation of tetravinylethylene/tetraethynylethylene hybrids . In stark contrast to the extensive work on [3]dendralenes, surprisingly few [4]dendralenes have been prepared, and no general synthesis exists. ,,, The present article addresses this deficiency and demonstrates how substitution can control the powerful Diels–Alder reactivity of [4]dendralene …”
The first general synthesis of branched tetraenes ([4]dendralenes)
involves two or three steps from inexpensive, commodity chemicals.
It involves an unprecedented variation on Suzuki–Miyaura cross-coupling,
generating two new C–C bonds in a one-flask operation with
control of diastereoselectivity. The broad scope of the method is
established through the synthesis of more than 60 diversely substituted
[4]dendralene molecules, along with substituted buta-1,3-dienes and
other [n]dendralenes. [4]Dendralenes are demonstrated
to be significantly more kinetically stable than their well-known
[3]dendralene counterparts. The first stereoselective synthesis of
these compounds is also reported, through the catalyst-controlled
generation of both E- and Z-diastereomeric
products from the same precursor. Novel, through-conjugated/cross-conjugated
hybrid molecules are introduced. The first selective dienophile cycloadditions
to substituted [4]dendralenes are reported, thus paving the way for
applications in target-oriented synthesis.
“…They also serve as useful chemical motifs for the synthesis of functional compounds . In particular, tetraphenylethylene (TPE), tetravinylethylene (TVE), tetraethynylethylene (TEE), and their derivatives have attracted much attention in the past several decades. They have demonstrated plenty of applications in optoelectronic devices, fluorescent chemosensors, bioimaging, and biosensors due to their organic π-conjugated frameworks resulting in unique phenomenon properties in solid and aggregated states (Scheme A) .…”
The π-bond enrichment frameworks not only serve as a crucial building block in organic synthesis but also assume a pivotal role in the fields of materials science, biomedicine, photochemistry, and other related disciplines owing to their distinctive structural characteristics. The incorporation of various substituents into the C�C double bonds of tetrasubstituted alkenes is currently a highly significant research area. However, the synthesis of tetrasubstituted alkenes with diverse substituents on double bonds poses a significant challenge in achieving stereoselectivity. Here, we reported an efficient and convergent route of Cu-catalyzed borylalkynylation of both symmetrical and unsymmetrical 1,3-diynes, B 2 pin 2 , and acetylene bromide to the construction of boronated phenyldiethynylethylene (BPDEE) derivatives with excellent chemo-, stereo-, and regioselectivities. BPDEE derivatives could transform into novel tetrasubstituted organic πconjugated gem-diphenyldiethynylethylene (DPDEE), vinylphenyldiethynylethylene (VPDEE), and phenyltriethynylethylene (PTEE) derivatives by a stepwise process, which provides a flexible platform for the synthesis of complex π-bond enrichment frameworks that were difficult to synthesize by previous methods. The initial optical characterization revealed that the synthesized molecules exhibited aggregation-induced emission (AIE) properties, which further establishes the groundwork for future applications and enriches and advances the field of functional π-conjugated frameworks research.
“…Their biological activity stems from the generation of diradicals, which is responsible for DNA cleavage and cell destruction 5 . Beyond their anticancer prospects, enynes also represent elementary units in synthetic chemistry and materials science, which undergo transformations to build functional compounds and π-conjugated frameworks 6 , 7 . Fig.…”
Belonging to the enyne family, enetriynes comprise a distinct electron-rich all-carbon bonding scheme. However, the lack of convenient synthesis protocols limits the associated application potential within, e.g., biochemistry and materials science. Herein we introduce a pathway for highly selective enetriyne formation via tetramerization of terminal alkynes on a Ag(100) surface. Taking advantage of a directing hydroxyl group, we steer molecular assembly and reaction processes on square lattices. Induced by O2 exposure the terminal alkyne moieties deprotonate and organometallic bis-acetylide dimer arrays evolve. Upon subsequent thermal annealing tetrameric enetriyne-bridged compounds are generated in high yield, readily self-assembling into regular networks. We combine high-resolution scanning probe microscopy, X-ray photoelectron spectroscopy and density functional theory calculations to examine the structural features, bonding characteristics and the underlying reaction mechanism. Our study introduces an integrated strategy for the precise fabrication of functional enetriyne species, thus providing access to a distinct class of highly conjugated π-system compounds.
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