A straightforward double intramolecular cyclization of dibenzyl dichalcogenols into a triple bond

Sashida, Haruki; Kaname, Mamoru; Nakayama, Akemi; Suzuki, Hirokazu; Minoura, Mao

doi:10.1016/j.tet.2010.04.101

Cited by 22 publications

(9 citation statements)

References 33 publications

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“…Chemical diagrams for tellurium(II) compounds described herein, 125-151, 82,[125][126][127][128][129][130][131][132][133][134][135][136][137][138] forming…”

Section: Zero-and One-dimensional Aggregates Sustained By Te(ii) … π(mentioning

confidence: 99%

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Main group metal lone-pair⋯π(arene) interactions: a new bonding mode for supramolecular associations

et al. 2016

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Crystal structures of the heavier main group elements in low oxidation states have been evaluated for the presence of supramolecular element(lp)⋯π(arene) interactions that are structure-directing. It is revealed that when present, these interactions lead to zerodimensional, binuclear aggregates but higher-nuclearity species are sometimes observed, with one-dimensional supramolecular chains of varying topology being prominent. By contrast, two-dimensional aggregation based on element(lp)⋯π(arene) interactions are rare. In summary, interactions of main group metal lone-pairs with aromatic rings are revealed as synthons capable of assembling molecules into supramolecular aggregates. † Electronic supplementary information (ESI) available: For ESI (illustrations of supramolecular aggregation based on main group element(lone-pair)⋯π(arene) interactions for 1-157), see DOI:

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“…Chemical diagrams for tellurium(II) compounds described herein, 125-151, 82,[125][126][127][128][129][130][131][132][133][134][135][136][137][138] forming…”

Section: Zero-and One-dimensional Aggregates Sustained By Te(ii) … π(mentioning

confidence: 99%

“…22b. 137 where the telluroether-rather than the telluride-tellurium(II) atom forms the interaction, leading to a zigzag chain, Fig. 22g.…”

Section: Zero-and One-dimensional Aggregates Sustained By Te(ii) … π(mentioning

confidence: 99%

Main group metal lone-pair⋯π(arene) interactions: a new bonding mode for supramolecular associations

et al. 2016

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“…Treatment of 11 with butyllithium was followed by iodination to afford 12, which was then used for the second Sonogashira coupling reaction with propargyl alcohol resulting in the formation of the cross-coupling adduct 13 in 84% overall yield from 11. The exposure of 13 to Cu(OAc) 2 ·H 2 O effected the consecutive removal of the trimethylsilyl (TMS) group and homo-coupling of the terminal alkyne moiety 29) to afford the tetrayne 14 in 89% yield. The Mitsunobu reaction of 14 with diisopropyl azodicaroboxylate (DIAD) and N-isopropylidene-N′-2-nitrobenzenesulfonyl hydrazine (IPNBSH) was followed by hydrolysis under trifluoroethanol (TFE)/water conditions 30) to produce the bis(allenyne) 7, a substrate of PKTR, in 63% yield (Chart 4).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of a Carbon Analogue of Scytonemin

Mukai

Arima

Hirata

et al. 2015

CHEMICAL & PHARMACEUTICAL BULLETIN

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The synthesis of a carbon analogue of scytonemin was accomplished on the basis of molybdenummediated intramolecular double Pauson-Khand type reaction of bis(allenyne), followed by the double aldol condensation of the formed double Pauson-Khand type adduct.Key words scytonemin; allene; [2+2+1] cycloaddition; alkyne; molybdenum; aldol condensation Scytonemin (1) is the cyanobacterial dimeric alkaloid pigment, whose chemical structure has been elucidated by Gerwick and co-workers in 1993, 1) over 100 years after its discovery. Scytonemin has an intriguing novel structural feature, which consists of a two 1,1′-linked cyclopent [b] indole-2(1H)-one framework possessing 4-hydroxybenzylidenes at the 3-positions of the fused tricyclic systems. The biosynthetic studies of scytonemin have been recently made by Walsh and Balskus.2,3) In 2011, Mårtensson and colleagues achieved the first total synthesis of scytonemin by taking advantage of the tandem Heck carbocyclization/Suzuki-Miyaura coupling and a bioinspired oxidative dimerization. 4) Of particular interest is its interesting biological features. Scytonemin is a UVabsorbing pigment that protects important cellular components in a cyanobacteria against harmful UV radiation. [5][6][7][8] Besides this important function, scytonemin exhibits a biological activity as a small molecule inhibitor of polo-like kinase 1 9) and possesses anti-inflammatory and antiproliferative properties. 10)During our studies on the syntheses of various kind of alkaloids, [11][12][13][14][15][16][17][18][19] we became very interested in the highly conjugated and characteristic dimeric structure of scytonemin as well as its biological activity. We postulated that the origin of the biological activity of scytonemin (1) might be elucidated by comparison with its carbon analogue, in which two nitrogen atoms are replaced by two carbon atoms. Therefore, our endeavor was directed toward the synthesis of 2, a carbon analogue of scytonemin (1) (Chart 1).In 2005, Liu and Datta developed the efficient synthesis of 1H-cyclopent[a] inden-2-one (4a) from 1-ethynyl-2-(1,2-propadienyl) benzene (3a) through the Mo(CO) 3 (MeCN) 3 -mediated carbonylative [2+2+1] ring-closing reaction at 25°C in a stoichiometric manner 20) (Chart 2). They also reported the catalytic version of that transformation in the presence of 5 mol% of [RhCl(CO) 2 ] 2 at 90°C to furnish 4a in 62% yield along with the by-production of 2-methylnaphthalene (5), the latter of which should be arisen from the MyersSaito cycloaromatization 21-25) of 3a. We have independently reported that treatment of 3-(2-ethynylphenyl) prop-2-ynyl benzenesulfinate (6) with 2.5 mol% of [RhCl(CO) 2 ] 2 at 40°C in an atmosphere of CO effected the successive 2,3-sigmatropic rearrangement and carbonylative [2+2+1] ring-closing reaction of the resulting allenyne species 3b to afford the 8-(phenylsulfonyl)-1H-cyclopent[a] inden-2-one (4b) in a high yield.26) In this case, the formation of 2-methylnaphthalene could not be detected in the reaction mixture. We now report t...

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“…With the exception of one structure, the remaining tellurium structures featuring Te(lone pair)···π (aryl) synthons, that is, 23-38 [38,[41][42][43][44][45][46][47][48][49][50][51][52][53] adopt one-dimensional aggregation patterns in their crystal structures, see Table 12.3 for data. There are basically two variations in that the majority, 11 examples, that is, 23-33, have the chains sustained by single Te(lone pair) ··π (aryl) interactions, whereas there are five examples whereby the chains are sustained by two Te(lone pair) .…”

Section: Scheme 123 (Continued)mentioning

confidence: 99%

Supramolecular Aggregation Patterns and Stereochemical Consequences of Tellurium(Lone Pair)…π(Aryl) Interactions

Haiduc

Tiekink

Zukerman-Schpector

2012

The Importance of Pi‐Interactions in Crystal Engineering

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While the formation of π-aryl bonds is typical for transition metals, the main-group elements display a reduced tendency to form π -aryl complexes. This being stated, it was established by the report of the so-called "Menschutkin's complexes", for example, C 6 H 6 .SbCl 3 [1], that main-group element compounds can and do form such interactions. In the case of transition-metal systems, metal···π interactions are readily rationalised in terms of electron donation from the electron-rich aryl system to the electropositive metal centre. By contrast, allied interactions with main-group elements, often having a lone pair of electrons, seems counterintuitive. However, as indicated from macromolecular chemistry [2,3], heteroatom(lone pair)···π (aryl) interactions are stabilising. Theoretical studies indicate energies of stabilisation ranging from 1.5 to 5.1 kJ mol −1 [4,5]. The heteroatom(lone

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A straightforward double intramolecular cyclization of dibenzyl dichalcogenols into a triple bond

Cited by 22 publications

References 33 publications

Main group metal lone-pair⋯π(arene) interactions: a new bonding mode for supramolecular associations

Main group metal lone-pair⋯π(arene) interactions: a new bonding mode for supramolecular associations

Synthesis of a Carbon Analogue of Scytonemin

Supramolecular Aggregation Patterns and Stereochemical Consequences of Tellurium(Lone Pair)…π(Aryl) Interactions

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