Diazadiene als Steuerliganden in der homogenen Katalyse XIX. Palladium-katalysierte 2:2-Cyclisierung eines Alkins mit Allenen zu Naphthalin-2,3,6,7-tetracarbonsäurederivaten
“…tom Dieck's group reported the synthesis of tetrasubstituted naphthalene ester 635 , an important class of organic compounds for the preparation of polyimides from the reaction of 2 mol of allenes with 2 mol of acetylene dicarboxylate 632 in the presence of diazadiene-stabilized palladacyclopentadiene 633 as the catalyst (Scheme ). Compound 635 can be obtained from the reaction of 1,2-propadiene ( 40 ) in high yield by a two-step procedure and by a novel one-step procedure from allenic ethers 232 and 630 , of course in diminished yields, both via 634 . , Interestingly, in the case of phenoxyallene ( 631 ) and methylallene 533 , no 635 but cotrimerization product 636 was formed, possibly due to steric reasons. 172 …”
Section: Di- Oligo- and Polymerization Reactions Of
Allenesmentioning
confidence: 99%
“…Compound 635 can be obtained from the reaction of 1,2-propadiene (40) in high yield by a two-step procedure and by a novel one-step procedure from allenic ethers 232 and 630, of course in diminished yields, both via 634. 192,193 Interestingly, in the case of phenoxyallene (631) and methylallene 533, no 635 but cotrimerization product 636 was formed, possibly due to steric reasons. Do ¨hring and Jolly studied the palladium-catalyzed co-oligomerization of 1,2-propadiene (40) and carbon dioxide leading to a mixture of esters 637 and 639, δ-lactone 638, hydrocarbon oligomers, and polymer (Scheme 173).…”
Section: Di- Oligo- and Polymerization Reactions Of Allenesmentioning
“…tom Dieck's group reported the synthesis of tetrasubstituted naphthalene ester 635 , an important class of organic compounds for the preparation of polyimides from the reaction of 2 mol of allenes with 2 mol of acetylene dicarboxylate 632 in the presence of diazadiene-stabilized palladacyclopentadiene 633 as the catalyst (Scheme ). Compound 635 can be obtained from the reaction of 1,2-propadiene ( 40 ) in high yield by a two-step procedure and by a novel one-step procedure from allenic ethers 232 and 630 , of course in diminished yields, both via 634 . , Interestingly, in the case of phenoxyallene ( 631 ) and methylallene 533 , no 635 but cotrimerization product 636 was formed, possibly due to steric reasons. 172 …”
Section: Di- Oligo- and Polymerization Reactions Of
Allenesmentioning
confidence: 99%
“…Compound 635 can be obtained from the reaction of 1,2-propadiene (40) in high yield by a two-step procedure and by a novel one-step procedure from allenic ethers 232 and 630, of course in diminished yields, both via 634. 192,193 Interestingly, in the case of phenoxyallene (631) and methylallene 533, no 635 but cotrimerization product 636 was formed, possibly due to steric reasons. Do ¨hring and Jolly studied the palladium-catalyzed co-oligomerization of 1,2-propadiene (40) and carbon dioxide leading to a mixture of esters 637 and 639, δ-lactone 638, hydrocarbon oligomers, and polymer (Scheme 173).…”
Section: Di- Oligo- and Polymerization Reactions Of Allenesmentioning
“…The synthesis of palladacyclopentadienes bearing electron-withdrawing substituents has been reported previously . These compounds were found to be intermediates in the Pd(0)-catalyzed cyclotrimerization of acetylenes, which has been extensively studied together with the cocyclotrimerizations of acetylenes with other acetylenes, alkenes, and allenes 2,6-lutidine, and Ph 3 PC 5 H 4 (triphenylphosphonium cyclopentadienylide) as ligands are known.…”
Palladacyclo-2,4-pentadiene compounds containing a chelating
bidentate nitrogen ligand
Pd{(C(E)C(E)-C(E)C(E)}(NN)
1a−f (E = CO2Me, NN =
Ph-bip, Ar-bian, bpy, dcm-bpy,
bpym) and 2a,b (E = CF3, NN =
Ph-bip, (p-tol)-bian) have been prepared from
Pd(dba)2,
the appropriate bidentate N-ligand, and electron-deficient acetylenes
dimethyl 2-butynedioate
or hexafluorobutyne. X-ray crystal structures were obtained for
compounds 1a (NN = Ph-bip) and 1d (NN = 2,2‘-bpy). In solution, an
equilibrium between the monomer and a dimer
exists for compounds 1d and 1e (NN =
bipyrimidine); in the solid state, 1d is a
monomer.
The dimeric form of 1d is of the same type as the
zerovalent palladium compound [(μ-3,3‘-dicarbomethoxy-2,2‘-bipyridine)Pd(tcne)]2 in
which the two bipyridine derivatives bridge
between the two palladium centers, as determined from the X-ray crystal
structure of this
compound (7). The palladacycles 1 undergo
oxidative addition of methyl iodide, benzyl
bromide, or iodobenzene. Subsequent reductive elimination gives
rise to the formation of
4-functionalized 1,3-dienylpalladium(II) halide compounds
3−5 (cis arrangement of the ester
functions at the double bonds). In the reaction with an excess of
1,4-chloro-2-butyne, a
trimerization took place forming
1-(1‘-chloroethenyl)-1,2,3,4,5-pentakis(chloromethyl)-2,4-cyclopentadiene (6). Employing the established kinetic
compatibility of the formation of
the palladacycles with a successive oxidative addition/reductive
elimination of organic halides
and subsequent transmetalation with tetramethyltin, a catalytic cycle
for the three-component synthesis of (Z,Z)-dienes of the type
R−C(E)C(E)C(E)C(E)CH3
(8, R = alkyl,
aryl; E = CO2CH3) has been conceived,
e.g., from dimethyl 2-butynedioate, an organic halide,
and tetramethyltin employing 1% of 1b as the catalyst in
DMF. This constitutes the first
catalytic synthesis of conjugated dienes from alkynes.
Pd(phosphine) compounds do not
catalyze this reaction.
“…To simplify the discussion, we decided to arrange these agents based on their discovery in chronological order. The discussion begins with the example that was reported by Dieck’s research group in 1990 for a 1:2 coupling of allene and alkyne (Scheme A) . Diazadiene-stabilized palladacyclopentadiene was discovered to be capable of catalyzing the coupling of an allene with ADC ( 2b ) only in the specific instance when phenoxyallene ( 36a ) was employed.…”
Section: Aa Coupling In Constructing
Cyclic C-skeletonsmentioning
Because of its wide applicability in the synthesis of diverse unsaturated building blocks, allene−alkyne (AA) coupling has emerged as a powerful methodology to drive useful chemical transformations in the past two decades. Considering recent discoveries in this active research area, in this Review, we aim to support chemists in the selection of suitable methods, particularly intermolecular approaches, according to the synthesis needs. However, inherent similarities between the reactivities of π-systems create considerable obstacles while predicting selectivity in an intermolecular platform. Therefore, herein, intermolecular couplings for the chemoselective, stereoselective, and regioselective syntheses of acyclic and cyclic C-skeletons are reviewed. However, considering the lack of a well-organized review in this field, we initially provide a brief historical overview of the types of thermally induced reactions that are mostly feasible for electronically biased coupling components and are nonselective. Subsequently, emerging selective strategies are described, which include activator-controlled and neighboring functional group-assisted regio-, stereo-, and π-skeleton-divergent processes. Overall, this Review is divided into two parts. In the first part, strategies for the fabrication of acyclic C-skeletons are explained according to the reaction types. In the second part, synthetic transformations affording cyclic structures are reviewed based on the substrate class (that is, nonassisted and assisted substrates). Key reaction intermediates of each subset of coupling and factors affecting productselective discrimination of the active species with the highlight of rationale are systemically summarized. Understanding of these substrate structure-and catalyst-dependent factors provides insights into the regulation of the chemoselectivities of title AA crosscouplings and, therefore, the design of alternative catalytic routes with distinct mechanistic features.
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