Heck self-condensation of polycyclic haloalkenes: the case of (1R)-2-iodobornene

Zambrini, Laura; Fabris, Fabrizio; Lucchi, Ottorino De; Gardenal, Graziano; Visentin, Fabiano; Canovese, Luciano

doi:10.1016/s0040-4020(01)00850-x

Cited by 19 publications

(7 citation statements)

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“…20 However, the use of enantiomerically pure starting materials led to very low yields (5%) of syn-cyclotrimers. 21 More recently, the optimization of the reaction conditions by the group of H. Sakurai have opened an interesting alternative for the synthesis of BCT. 22 Pd-catalyzed cyclotrimerization of enantiopure iodonorbornens have been applied to preparation of C 3 or C 3v symmetric BCTs with various functional groups.…”

Section: Benzocyclotrimers: Synthesismentioning

confidence: 99%

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

et al. 2011

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The formal annulation of three bicylic olefins yields a class of molecules termed benzocyclotrimers (BCTs), which have unusual electronic properties. The bonds in the central aromatic ring, for example, alternate in length: rather than resembling a substituted benzene, a BCT instead evokes comparison to a cyclohexatriene. Forty years have passed since the synthesis of heptiptycene, the first BCT, was reported. In the interim, many methods have been developed for preparing tris-bicycloannulated benzenes. More than thirty different BCTs have so far been reported, with a variety of morphological features and properties. Over the same period, yields have increased from just a few percent to almost quantitative conversion. This improvement in synthetic access has expanded interest beyond the original theoretical considerations (bond-length fixation in aromatics) to functional applications (supramolecular scaffolds). In this Account, we describe the evolution of synthetic approaches to BCTs and their derivatives, as well as the applications that are now being explored for these compounds. Early syntheses of BCTs involved chloroolefins treated with butyl lithium. A strained alkyne intermediate was postulated early on, and was indeed trapped in 1981. Subsequent efforts have focused on improving chemoselectivity by mitigating the drastic conditions required for the generation of the alkyne intermediate. Our introduction of Cu(I) to induce lithium-copper exchange was successful in this regard. Further improvement resulted from the use of bicylic bromo(trimethylstannyl)olefins. In an effort to avoid the toxicity of the tin reagents, the Heck reaction and Pd catalysis have been pursued for cyclotrimerizing bicylic bromo- and iodoolefins. Depending on the symmetry of the starting bicylic olefin, two diastereomers can be obtained in the preparation of a BCT: a syn compound with C(3) symmetry and an anti compound with C(s) symmetry. Studying the diastereomeric outcome in a variety of synthetic approaches has yielded valuable insight into the cyclotrimerization reaction. Moreover, highly symmetric compounds, such as a D(3)-symmetric trindane and C(3v)-symmetric sumanene, have been prepared as BCT derivatives. The structure of BCTs offers a versatile three-dimensional scaffold for studying molecular recognition. Like calixarenes, BCTs form complexes with a variety of guest molecules. Recent developments include the trapping of gases in a hydrogen-bonded dimer and the encapsulation of larger molecules within a covalently linked condensation derivative. Future innovations in this fertile research area will likely include highly functionalized curved aromatics, receptors, and sensors.

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Section: Benzocyclotrimers: Synthesismentioning

confidence: 99%

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

et al. 2011

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“…This is partially imputable to the concomitant formation of significant amounts (17 % yield) of dimer 11 , formed by homocoupling of iodide 10 . This reaction pathway probably involves a palladium(IV) intermediate,20c which can be reintroduced into the catalytic cycle by acetate ion acting as a reducing agent 26…”

Section: Resultsmentioning

confidence: 99%

“…[19] These methodologies suffer from the need for stannylated starting material and several protection/deprotection steps for the copper-mediated cyclotrimerization re-action. To shorten the synthetic route, skipping the stannylation step and improving the final yields, an alternative Heck-type cyclotrimerization strategy [20] has been applied. A suitable building block for the cyclotrimerization was obtained in three steps (Scheme 1) starting from hydrazone 8, [15,21] which was iodinated in the presence of N,N,N,N-tetramethylguanidine (TMG) [22] to furnish the corresponding vinyl iodide 9.…”

Section: Resultsmentioning

confidence: 99%

Chiral M₃L₂ Self‐Assembled Capsules through Metal Coordination of Enantiopure Ligating Benzocyclotrimers: NMR Spectroscopic and ESI Mass Spectrometric Investigation

Tartaggia¹,

Lucchi²,

Gambaro³

et al. 2013

Chemistry A European J

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The synthesis of enantiopure (+)-benzotricamphor syn-5, an important chiral C3-symmetric rigid building block for supramolecular applications, was studied in detail to reduce the number of steps and to increase the diastereoselectivity and overall yield. The new synthetic procedure allowed larger amounts of syn-5 to be obtained and used for the preparation of new derivatives, such as the corresponding tris-trifluoromethanesulfonate syn-12, which was efficiently transformed into (+)-benzotribornenetrinitrile syn-1 and (+)-benzotribornenetris(ethynyl-4-pyridine) syn-2. The previously reported (+)-benzotricamphortrioxime syn-6 was transformed into tris-nitrile syn-3 by Beckman reaction. Compounds syn-1-3 were employed as multidentate ligands for silver(I) and platinum(II) centres in apolar solvents. The linear coordination geometry of Ag(I) and square-planar geometry of cis-chelated Pt(II) in combination with the chiral tripodal ligands syn-1-3 led to the formation of chiral enantiopure capsules with M3 L2 stoichiometry, as confirmed by 2D NMR NOESY and DOSY experiments as well as ESI mass spectrometry.

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“…207,208 The Heck reaction of (1R)-2-iodobornene gave trimeric benzene products in low yield. 209 The nonplanar fused aromatic system 180 was prepared by the palladium-catalysed cyclotrimerization of 9,10-didehydrophenanthrene. 210 The efficient synthesis of fully annelated benzene 9 was achieved by the copper-catalysed coupling of 2,3-diiodobicyclo[2.1.1]hex-2-ene.…”

Section: (B) Metal-catalysed Cyclizationmentioning

confidence: 99%

7 Aromatic chemistry

Toyota

Iyoda

Toda

2002

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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Heck self-condensation of polycyclic haloalkenes: the case of (1R)-2-iodobornene

Cited by 19 publications

References 30 publications

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

Chiral M₃L₂ Self‐Assembled Capsules through Metal Coordination of Enantiopure Ligating Benzocyclotrimers: NMR Spectroscopic and ESI Mass Spectrometric Investigation

7 Aromatic chemistry

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Heck self-condensation of polycyclic haloalkenes: the case of (1R)-2-iodobornene

Cited by 19 publications

References 30 publications

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

Chiral M3L2 Self‐Assembled Capsules through Metal Coordination of Enantiopure Ligating Benzocyclotrimers: NMR Spectroscopic and ESI Mass Spectrometric Investigation

7 Aromatic chemistry

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Chiral M₃L₂ Self‐Assembled Capsules through Metal Coordination of Enantiopure Ligating Benzocyclotrimers: NMR Spectroscopic and ESI Mass Spectrometric Investigation