Efficient Cyclotrimerization of Bicyclic <i>v</i><i>ic</i>-Bromostannylalkenes Promoted by Copper(I) Thiophen-2-carboxylate

Borsato, Giuseppe; Lucchi, Ottorino De; Fabris, Fabrizio; Groppo, Luca; Lucchini, Vittorio; Zambon, Alfonso

doi:10.1021/jo020396s

Cited by 40 publications

(13 citation statements)

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“…In order to accomplish the cyclotrimerization, the vic-bromostannane 9 was treated with copper(I) 2-thiophenecarboxylate (CuTC) in dry NMP (N-methyl-2-pyrrolidone) at low temperature. 36 The two isomeric benzocyclotrimers were formed in a highly favourable 7:3 syn to anti ratio and in a very good isolated yield (92%). The selectivity was opposite to the expected statistical distribution observed in the majority of cyclotrimerization reactions.…”

Section: Resultsmentioning

confidence: 95%

Highly diastereoselective synthesis of a novel functionalized benzocyclotrimer

Erdoğan¹,

Eşsiz²,

Fabris³

et al. 2018

Arkivoc

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The high yielding synthesis of a novel benzocyclotrimer is herein presented. The syn-diastereomer is obtained as major product, presumably in virtue of the presence of an oxa-bridge of the bicylic components. The three oxa-bridges can be used for further functionalization, as well as the six bromine atoms of the three aromatic rings, as demonstrated in the aromatization of a mixture of anti-1 and syn-1 (3:7) leading to trinaphthylene.

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Section: Resultsmentioning

confidence: 95%

Highly diastereoselective synthesis of a novel functionalized benzocyclotrimer

Erdoğan¹,

Eşsiz²,

Fabris³

et al. 2018

Arkivoc

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“…Acetal 6 was stannylated with LDA and chlorotrimethylstannane furnishing the vic ‐bromostannylolefin 7 in 79% yield 68. The cyclotrimerization of 7 was accomplished with copper(I) 2‐thiophenecarboxylate (CuTC),72 to produce a 6.8:1 syn to anti ratio mixture of cyclotrimers 2 in 70% overall yields (Scheme ). The favorable diastereoselectivity results from the presence of sterically hindered trimethyltin moiety and scarcely hindered ligating functional group in the enantiopure bicyclic olefin, as previously observed with related substrates 73, 74…”

Section: Resultsmentioning

confidence: 99%

Synthesis, chiroptical properties, and their theoretical simulation of some highly rotating benzotricamphor derivatives

Mazzeo¹,

Giorgio²,

Rosini³

et al. 2009

Chirality

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The large molecules 1-3 (69, 90, and 102 atoms, respectively), prepared by cyclotrimerization of enantiomerically pure derivatives of (2)-bornyl acetate, show intense ECD spectra, high optical rotation (OR) values (200-1300, in absolute value) dominated in sign and order of magnitude by the lowest-energy Cotton effects, that is, they are the ideal candidates to test the reliability of our ''approximate'' (TDDFT/B3LYP/6-31G* or smaller basis set) approach to the calculation of chiroptical properties. As a matter of fact, a correct simulation of the OR values and ECD spectra of 1 and 2 can be obtained even using STO-3G basis set and semiempirical or molecular mechanics input geometries: for 1, at the TDDFT/B3LYP/STO-3G level, the OR values are of the order of 500-550, versus an experimental value ranging between 660 and 690, depending on the solvent. On the contrary, the case of 3 (exp. OR between 21330 and 21500) is really complex (for instance, the OR values range between 23216 and 2729 (TDDFT/B3LYP/6-31G* calculations) or 21824 and 2444 (TDDFT/B3LYP/STO-3G calculations)), making the comparison between calculated and experimental values more difficult. The behavior of 3 is due to its molecular flexibility, whereas 1 is a really rigid molecules and 2 behaves (vide infra) as it were a rigid system. These observations strongly indicate that the conformational freedom constitutes one of the major difficulties for a correct but simple simulation of the chiroptical properties.

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“…Compound anti-3: mp 215°C (dec). 1 MeONa was generated in situ by reaction of 5 mL dry MeOH and Na (27.5 mg, 1.2 mmol). The solvent was removed, thiophenol (0.125 mL, 1.2 mmol) and a solution of syn-3 (50 mg, 0.1 mmol) in NMP (5 mL) were added.…”

Section: Methodsmentioning

confidence: 99%

Tris-Annelated Benzenes Selectively Perfunctionalized on One Side Only: Hexachlorobenzotrinorbornadiene as a Versatile Scaffold for the Construction of Molecular Domes

Borsato¹,

Brussolo²,

Crisma³

et al. 2005

Synlett

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H e x a c h l o r o b e n z o t r i n o r b o r n a d i e n e f o r t h e C o n s t r u c t i o n o f M o l e c u l a r D o m e sAbstract: Well-defined, rigid molecular domes are obtained via substitution of the chlorine atoms of hexachlorobenzotrinorbornadiene syn-3, efficiently synthesized in 1:2 ratio along with its antiisomer by CuTC-promoted cyclotrimerization of 3-bromo-2-trimethylstannylnorbornadiene 8. The three dichlorovinyl functions at the edge of syn-3 are displaced by sulfur nucleophiles and Grignard reagents with Ni(II)Cl 2 dppe as catalyst, gaining the persubstituted vinyl sulfides 9 and 10, and persubstituted methyl 12 and phenylethynyl 13.Structures in which a benzene ring is embedded in a molecular framework, functionalized only on one side of the aromatic plane, are attractive cores for the construction of larger molecular architectures, such as dendrimers and discotic liquid crystals. The structure sketched by the formula syn-1 (Scheme 1), with six reactive functionalities at the edge, combines the proprieties of concavity and rigidity with the possibility of different derivatizations. Scheme 1We have recently shown 1,2 that similar structures can be quantitatively obtained by the cyclotrimerization reaction of the appropriate monomer 2, functionalized at the vinyl end by bromine and trimethylstannyl groups, via the promotion of copper(I) 2-thiophenecarboxylate (CuTC). 3 We have also explored the reactivity in Diels-Alder reactions of one functionalized syn cyclotrimer with three diene systems at the edge. 2 The cyclotrimerization reaction affords both the syn-1 and the anti-1 isomers. The development of this project requires high yield in the first isomer, possibly exceeding the 1:3 syn/anti statistical ratio.We report in this paper the synthesis of the syn-3 and anti-3 cyclotrimers, characterized by the presence of three dichlorovinyl moieties. Among the synthetic uses of these substrates, the formations of C-S bonds from aliphatic and aromatic thiols, and of new C-C bonds through the use of metal-catalyzed cross-coupling are explored.The syn-3 and anti-3 cyclotrimers were obtained by the synthetic sequence illustrated in Scheme 2. Because of the high reaction temperature, the Diels-Alder addition of trichloroethylene to cyclopentadiene 4 does not require the formation of the latter by distillation of the cyclopentadiene dimer. Although the yield of the two isomers 5 is rather low, the inexpensive reagents make this step economically attractive. The bromination with molecular bromine is not stereoselective, and no Wagner-Meerwein rearrangement was observed. 5 The mixture of adducts 6 is then dehydrohalogenated with t-BuOK, gaining 7 as single product. The stannylation with Me 3 SnCl and LDA gives the monomer 8, and is followed by the action of CuTC. The syn-3 and anti-3 isomers, obtained with a 90% yield and in 1:2 ratio, have been separated by flash chromatography. 6 This straightforward synthetic path, which does not require particular purifications, afforded the two isomers of 3 in mu...

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Efficient Cyclotrimerization of Bicyclic vic-Bromostannylalkenes Promoted by Copper(I) Thiophen-2-carboxylate

Cited by 40 publications

References 15 publications

Highly diastereoselective synthesis of a novel functionalized benzocyclotrimer

Highly diastereoselective synthesis of a novel functionalized benzocyclotrimer

Synthesis, chiroptical properties, and their theoretical simulation of some highly rotating benzotricamphor derivatives

Tris-Annelated Benzenes Selectively Perfunctionalized on One Side Only: Hexachlorobenzotrinorbornadiene as a Versatile Scaffold for the Construction of Molecular Domes

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