Abstract:trans‐Cyclododecen sowie Gemische von cis‐ und trans‐Cyclododecen verschiedenen Isomerenverhältnisses liefern bei Umsetzung mit Palladiumchlorid immer das gleiche Gemisch aus drei cis‐trans‐isomeren π‐Allyl‐Komplexen. Das Reaktionsprodukt aus 1‐Methyl‐cyclododecen‐(1) und Palladiumchlorid ist ein „exocyclischer”︁ π‐Allyl‐Komplex.
“…These trends are consistent with the known free energies for isomerization of cycloalkenes as a function of ring size. In the case of the cyclododecenyl system, originally examined by Hüttel, we find no evidence for the anti − anti complex, which would experience more significant nonbonding (transannular) effects than the anti − syn or the syn − syn isomers. 9 t 10 t…”
Section: Resultscontrasting
confidence: 58%
“…The following discussion is presented on that basis. The procedure involved heating an excess of the cycloalkene with PdCl 2 in HOAc until the rapidly formed brown η 2 -olefin palladium complex was transformed to the characteristically yellow η 3 -allyl complex (Hüttel procedure) …”
Section: Resultsmentioning
confidence: 99%
“…Palladation of various ( E , Z ) mixtures of cyclododecene ( 23 ) was examined by Hüttel, who concluded that three isomeric complexes ( 24a − 24c ) formed in the ratio 10:50:40, as shown in Figure . Palladation of a 2:1 ( E ):( Z ) mixture of cyclododecene has now been conducted and the structures of the η 3 -allyl complexes investigated in detail.…”
Section: Resultsmentioning
confidence: 99%
“…Palladation of certain cycloalkenes using PdCl 2 in aqueous acid was studied by Hüttel, and with cyclohexene and 1-methylcyclohexene, low yields of η 3 -allylpalladium complexes were obtained, along with reduction and dehydrogenation products. Subsequently, Trost reported that both alkenes could be palladated in high yield with a procedure utilizing PdCl 2 −NaCl−NaOAc−CuCl 2 −HOAc, with careful temperature control.…”
The dimeric η3-allylpalladium chloride complexes
formed from various cycloalkenes (C7−C13) and some methyl- and tert-butyl-substituted
cycloalkenes have been characterized by
1H and 13C NMR spectroscopy and in selected
cases by X-ray crystallography. The formation
of syn and anti isomers in the larger ring
systems is demonstrated, and complexes with a
rearranged ring system are formed from tert-butylcyclodecene
and tert-butylcyclododecene.
The sesquiterpene, carophyllene, is shown to form an
η3-allyl exocyclic complex, exclusively
from the (E)-double bond. Cis and trans isomers, with
respect to allyl group orientation in
these halo-bridged dimers, have been identified by low-temperature
(190K) NMR spectroscopy, and their interconversion (ΔG
⧧ ≈ 11
kcal/mol) is considered to involve a “cubic”
η3-allylpalladium chloride tetramer.
“…These trends are consistent with the known free energies for isomerization of cycloalkenes as a function of ring size. In the case of the cyclododecenyl system, originally examined by Hüttel, we find no evidence for the anti − anti complex, which would experience more significant nonbonding (transannular) effects than the anti − syn or the syn − syn isomers. 9 t 10 t…”
Section: Resultscontrasting
confidence: 58%
“…The following discussion is presented on that basis. The procedure involved heating an excess of the cycloalkene with PdCl 2 in HOAc until the rapidly formed brown η 2 -olefin palladium complex was transformed to the characteristically yellow η 3 -allyl complex (Hüttel procedure) …”
Section: Resultsmentioning
confidence: 99%
“…Palladation of various ( E , Z ) mixtures of cyclododecene ( 23 ) was examined by Hüttel, who concluded that three isomeric complexes ( 24a − 24c ) formed in the ratio 10:50:40, as shown in Figure . Palladation of a 2:1 ( E ):( Z ) mixture of cyclododecene has now been conducted and the structures of the η 3 -allyl complexes investigated in detail.…”
Section: Resultsmentioning
confidence: 99%
“…Palladation of certain cycloalkenes using PdCl 2 in aqueous acid was studied by Hüttel, and with cyclohexene and 1-methylcyclohexene, low yields of η 3 -allylpalladium complexes were obtained, along with reduction and dehydrogenation products. Subsequently, Trost reported that both alkenes could be palladated in high yield with a procedure utilizing PdCl 2 −NaCl−NaOAc−CuCl 2 −HOAc, with careful temperature control.…”
The dimeric η3-allylpalladium chloride complexes
formed from various cycloalkenes (C7−C13) and some methyl- and tert-butyl-substituted
cycloalkenes have been characterized by
1H and 13C NMR spectroscopy and in selected
cases by X-ray crystallography. The formation
of syn and anti isomers in the larger ring
systems is demonstrated, and complexes with a
rearranged ring system are formed from tert-butylcyclodecene
and tert-butylcyclododecene.
The sesquiterpene, carophyllene, is shown to form an
η3-allyl exocyclic complex, exclusively
from the (E)-double bond. Cis and trans isomers, with
respect to allyl group orientation in
these halo-bridged dimers, have been identified by low-temperature
(190K) NMR spectroscopy, and their interconversion (ΔG
⧧ ≈ 11
kcal/mol) is considered to involve a “cubic”
η3-allylpalladium chloride tetramer.
x-Allyl-palladiumchlorid-Komplexe, die in 2-Stellung ein CH3 und in 1-Stellung eine Carboxyl-, Ester-, Saureamid-oder Nitrilgruppe neben H oder Alkyl aufweisen, konnen manchmal besser aus den entsprechenden ungesattigten Malonsaurederivaten unter Decarboxylierung dargestellt werden als aus den monofunktionellen Derivaten. Die N MR-Spektren einiger der erhaltenen Allyl-Komplexe erfordern die Zuordnung von syn-und anti-Strukturen.
Hiirtel und SchmidJahrg. 101 7 8
After a brief introduction emphasizing the synthetic relevance of the allylic C–H activation step, evoking the first pioneering stoichiometric studies that sowed the “seeds” of this subject, and analyzing similarities and differences between a “classical” and a “direct” Pd‐catalyzed allylation process, this review outlines some selected examples of palladium‐catalyzed direct allylic functionalization. This old reaction, ignored for many years, is now living a new and exciting era.
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