Palladium‐katalysierte sechsfache Alkenylierung von Hexabrombenzol — ein interessanter Fall von Selbstorganisation

Prinz, Peter; Lansky, Annegret; Knieriem, Burkhard; Meijere, Armin de; Haumann, Thomas; Boese, Roland; Noltemeyer, M.

doi:10.1002/ange.19971091209

Cited by 16 publications

(11 citation statements)

References 39 publications

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“…Under optimized conditions {[PdCl 2 (PPh 3 ) 2 ], NaOH, toluene/THF (1:1), 100 8C, 24 h} the cross-coupling of 20 with 2 a gave hexakis-(tert-butylethenyl)benzene (1 a) in 73 % yield. [30] This corresponds to an average yield of 95 % for each cross-coupling step.…”

Section: Resultsmentioning

confidence: 99%

“…The sixfold Stille coupling was also successful with the trimethylsilyl(ethenyl)stannane 19 i and gave 1 i in an acceptable yield of 41 %. [30] However, the at- (20) with a variety of alkenylboronates in THF/toluene (1:1) at 100 8C (Scheme 5).…”

Section: Resultsmentioning

confidence: 99%

“…Stacking of the cup-shaped molecules of hexakis(tert-butylethenyl)benzene (1 a) in the crystal. [30,38] Figure 2. Stacking of the cup-shaped molecules of hexakis(trimethylsilylethenyl)benzene (1 i) in the crystal.…”

Section: Multifold Couplings With Other Perbromoarenesmentioning

confidence: 98%

“…Stacking of the cup-shaped molecules of hexakis(trimethylsilylethenyl)benzene (1 i) in the crystal. [30,38] This corresponds to a nearly quantitative yield (~99 %) for each newly generated CÀC bond. According to an X-ray structure analysis the six arms of 25 in the crystal are irregularly rotated out of the plane of the central core, with two neighboring arms up, the two next down, and the last two almost in the plane (Figure 5).…”

Section: Multifold Couplings With Other Perbromoarenesmentioning

confidence: 99%

“…[45a] This same effect was observed for hexakis-(tert-butylethe- (23) in the crystal. [30,38] Chem. Eur.…”

Section: Multifold Couplings With Other Perbromoarenesmentioning

confidence: 99%

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Six‐ and Eightfold Palladium‐Catalyzed Cross‐Coupling Reactions of Hexa‐ and Octabromoarenes

Stulgies

Prinz

Magull

et al. 2004

Chemistry A European J

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Palladium-catalyzed sixfold coupling of hexabromobenzene (20) with a variety of alkenylboronates and alkenylstannanes provided hexaalkenylbenzenes 1 in up to 73 % and 16 to 41 % yields, respectively. In some cases pentaalkenylbenzenes 21 were isolated as the main products (up to 75 %). Some functionally substituted hexaalkenylbenzene derivatives containing oxygen or sulfur atoms in each of their six arms have also been prepared (16 to 24 % yield). The sixfold coupling of the less sterically encumbered 2,3,6,7,10,11-hexabromotriphenylene (24) gave the desired hexakis(3,3-dimethyl-1-butenyl)triphenylene (25) in 93 % yield. The first successful cross-coupling reaction of octabromonaphthalene (26) gave octakis-(3,3-dimethyl-1-butenyl)naphthalene (27) in 21 % yield. Crystal structure analyses disclose that, depending on the nature of the substituents, the six arms are positioned either all on the same side of the central benzene ring as in 1 a and 1 i, making them nicely cup-shaped molecules, or alternatingly above and below the central plane as in 1 h and 23. In 27, the four arms at C-1,4,6,7 are down, while the others are up, or vice versa. Upon catalytic hydrogenation, 1 a yielded 89 % of hexakis(tert-butylethyl)benzene (23). Some efficient accesses to alkynes with sterically demanding substituents are also described. Elimination of phosphoric acid from the enol phosphate derived from the corresponding methyl ketones gave 1-ethynyladamantane (3 b, 62 % yield), 1-ethynyl-1-methylcyclohexane (3 c, 85 %) and 3,3-dimethylpentyne (3 e, 65 %). 1-(Trimethylsilyl)ethynylcyclopropane (7) was used to prepare 1-ethynyl-1-methylcyclopropane (3 d) (two steps, 64 % overall yield). The functionally substituted alkynes 3 f-h were synthesized in multistep sequences starting from the propargyl chloride 11, which was prepared in high yields from the dimethylpropargyl alcohol 10 (94 %). The alkenylstannanes 19 were prepared by hydrostannation of the corresponding alkynes in moderate to high yields (42-97 %), and the alkenylboronates 2 and 4 by hydroboration with catecholborane (27-96 % yield) or pinacolborane (26-69 % yield).

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Multifold Couplings With Other Perbromoarenesmentioning

confidence: 98%

Section: Multifold Couplings With Other Perbromoarenesmentioning

confidence: 99%

“…[45a] This same effect was observed for hexakis-(tert-butylethe- (23) in the crystal. [30,38] Chem. Eur.…”

Section: Multifold Couplings With Other Perbromoarenesmentioning

confidence: 99%

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Six‐ and Eightfold Palladium‐Catalyzed Cross‐Coupling Reactions of Hexa‐ and Octabromoarenes

Stulgies

Prinz

Magull

et al. 2004

Chemistry A European J

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Novel C3-Symmetric Molecular Scaffolds with Potential Facial Differentiation

2002

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The conversion of 1,3,5‐substituted benzene and mesitylene by electrophilic aromatic substitution and Sonogashira cross‐coupling, respectively, furnished the C3‐symmetric, hexasubstituted benzene derivatives 1 and 2 with an alternating substitution pattern. Based on the molecular scaffolds obtained, the two systems serve as model compounds for novel receptor molecules with distinct geometric features. X‐ray structures have been obtained for 1 and 2, which are discussed in regard to their aptitude as receptor platforms or supramolecular building blocks. By looking at the rotational barriers for the functional groups placed around the molecular scaffolds by variable temperature 1H NMR spectroscopy, 1 and 2 turn out to exist in rapidly interconverting conformations. The alignment of these potential binding groups around the molecular scaffolds should be strongly biased by specific interactions with suitable guest molecules.

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Organopalladium Chemistry

Bräse¹

2013

Organometallics in Synthesis

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Palladium‐katalysierte sechsfache Alkenylierung von Hexabrombenzol — ein interessanter Fall von Selbstorganisation

Cited by 16 publications

References 39 publications

Six‐ and Eightfold Palladium‐Catalyzed Cross‐Coupling Reactions of Hexa‐ and Octabromoarenes

Six‐ and Eightfold Palladium‐Catalyzed Cross‐Coupling Reactions of Hexa‐ and Octabromoarenes

Novel C3-Symmetric Molecular Scaffolds with Potential Facial Differentiation

Organopalladium Chemistry

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