4,5‐Bis(dimethylamino)phenanthren und 4,5‐Bis(dimethylamino)‐9,10‐dihydrophenanthren: Synthesen und „Protonenschwamm”︁‐Eigenschaften

Saupe, Thomas; Krieger, Claus; Staab, Heinz A.

doi:10.1002/ange.19860980521

Cited by 30 publications

(20 citation statements)

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“…[2,3] In this case, the resultant catalyst will have Lewis basic sites, while there are other cases in which catalytic Brønsted basic sites are preferred. [7] The proton sponges are diamines with neighboring atoms at short distances and aromatic frames, such as naphthalene, [8,9] fluorine, [10] heterofluorene, [11] phenanthrene, [12] and their analogues. Recently, a proton sponge, 1,8-bis(dimethylamino)naphthalene, with strong basicity, was used as an organic building block to produce organic-inorganic hybrid mesoporous materials with good catalytic properties.…”

Section: Introductionmentioning

confidence: 99%

Strong Organic Bases as Building Blocks of Mesoporous Hybrid Catalysts for C–C Forming Bond Reactions

et al. 2012

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1,8-Bis(tetramethylguanidino)naphthalene (TMGN), a neutral organic base that combines the properties of guanidine and the properties of proton sponges, was used as a building block to produce organic-inorganic silica-based mesoporous hybrids with strong basic properties. The TMGN-based mesoporous hybrids (TMGN/SiO 2 ) were prepared by a solgel route working at a neutral pH and low temperatures, which avoided the use of SDAs. TMGN has been modified in order to have two terminal reactive silyl groups able to [a] 5175 perform co-condensation with a conventional organosilane (TMOS) used as a silicon source. This synthesis has allowed us to directly introduce the unmodified, functionalized TMGN as part of the walls of the mesoporous silica by a onepot synthesis. TMGN/SiO 2 hybrid materials present excellent catalytic properties for C-C bond forming reactions: Knoevenagel, Henry (nitroaldol), and Claisen-Schmidt condensations. The activity of the hybrid materials is higher than that of the counterpart homogeneous catalyst.with a pK a of 12.1 in MeCN and PA(MP2) gas of 245.5 kcal mol -1 . The proton sponges are a matter of interest in current research investigations and the design of more basic proton sponges has received great attention. [14][15][16][17] By combining the proton sponge skeleton with two peralkyl guanidine functions, known for their strong proton affinity and high basicity, a neutral organic base, named 1,8-bis-(tetramethylguanidino)naphthalene (TMGN, Scheme 1) was recently obtained with an experimental pK a of 25 in MeCN and PA(MP2) gas of 257.5 kcal mol -1 . [18] Scheme 1. Scheme of 1,8-bis(dimethylamino)naphthalene (DMAN) and 1,8-bis(tetramethylguanidino)naphthalene (TMGN).

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Section: Introductionmentioning

confidence: 99%

Strong Organic Bases as Building Blocks of Mesoporous Hybrid Catalysts for C–C Forming Bond Reactions

et al. 2012

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“…As a result the ligand is distorted to a C 1 symmetry allowing the Pt atom to have an almost perfect square-planar coordination sphere ( Figure S10). [26] Similarly, the Br···Br distance in 17 and 18 (3.62 Å both) are equal to the sum of the van der Waals radii (1.85 Å); [22] the Br···Br distance is only 0.2 Å longer than in the highly strained 4,5-dibromophenanthrene. Consequently, Pd complexes 16 and 18 appear to benefit from similar stabilizing forces, which invoke a distorted backbone.…”

Section: Introductionmentioning

confidence: 99%

“…Depending on the phosphane groups [diphenylphosphanyl (11, 13) or diisopropylphosphanyl (12,14)] the palladium dichloride complexes show different coordination symmetry. [25][26][27] …”

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“…[22] Additionally, the dimethylamino groups can increase the electron density of the biphenyl system, [23] act as additional hemilabile donors [24] or form proton sponge systems. Synthetic route to biphenyl species 6 and 7 used for subsequent modifications.Starting from diamine 5, diiodo derivative 6 [36] as well as bis(dimethylamino) derivative 7 [26,27] were obtained by Sandmeyer (6) or N-methylation (7) reactions, respectively (Scheme 2). A particularly effective method has been the treatment of a 2,2Ј-di-www.eurjic.org FULL PAPER lithiated biphenyl with a chlorophosphane.…”

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Synthesis of 6,6′‐Bis(dimethylamino)‐ and 6,6′‐Dibromo‐Substituted 2,2′‐Diphosphanylbiphenyls and Their Palladium Complexes

et al. 2013

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New 6,6Ј-dibromo-and 6,6Ј-bis(dimethylamino)-substituted 2,2Ј-diphosphanylbiphenyl ligands 11-14 were prepared starting from 2,2Ј-dibromo-4,4Ј-dimethyl-6,6Ј-dinitro-1,1Ј-biphenyl (4). Depending on the phosphane groups [diphenylphosphanyl (11, 13) or diisopropylphosphanyl (12,14)] the palladium dichloride complexes show different coordination symmetry. Whereas the smaller diphenylphosphanyl groups lead to C 2 -symmetric complexes, the respective bis(diisopropyl)phosphanes 12 and 14 form C 1 -symmetric complexes that show fluxional behavior due to the restricted rotation of the isopropyl groups as well as the exchange of atom positions within the C 1 -symmetric conformer. All complexes have[a] TU Chemnitz, 4858 been tested as precatalysts in the Suzuki-Miyaura cross coupling reaction of 2-bromotoluene and phenylboronic acid. The activity of the catalytic system increases with the size of the diphosphanes and the donating ability of the ligand. In contrast to C 2 -symmetric palladium complex 15, platinum complex 19 was found to be C 1 -symmetric in the solid state despite the fact that both complexes have the small bis-(diphenylphosphanyl)-substituted diphosphane ligand 11 in common. NiBr 2 adduct 20 with a similar diphosphane 13 exists as a mixture of distorted square-planar and tetrahedral coordination sphere geometries in equilibrium with each other.Scheme 1. 1,1Ј-Biphenyl-2,2Ј-diyl-bridged diphosphanes discussed below and the numbering for relevant positions.phanes are of interest, as the large bromo substituents in the ortho positions lead to high activation barriers for the rotation around the central C-C bond. [22] Additionally, the dimethylamino groups can increase the electron density of the biphenyl system, [23] act as additional hemilabile donors [24] or form proton sponge systems. [25][26][27] Results and DiscussionLigands based on 2-phosphanyl-and 2,2Ј-diphosphanylbiphenyls are accessible by various methods employing electrophilic, [28] nucleophilic, [29] and radical chemistry [30] as well as transition-metal-catalyzed [31,32] reactions. A particularly effective method has been the treatment of a 2,2Ј-di-www.eurjic.org FULL PAPER lithiated biphenyl with a chlorophosphane. [28,33,34] Dilithiated biphenyl species are easily prepared by halogen/lithium exchange from the 2,2Ј-diiodo-/2,2Ј-dibromobiphenyls. We prepared diiodobiphenyl 6 and dibromobiphenyl 7 by the route depicted in Scheme 2. [35,36] The known diamine derivative 5 can be prepared from inexpensive and commercially available 4-methyl-2-nitroaniline (1). The methyl group in the 4-position blocks the C-4 atom from electrophilic attack by bromine in the first step to derivative 2; consequently, 2 is the only isolable regioisomer. [37] Moreover, the 4-methyl group improves the solubility of all compounds and simplifies workup procedures. The key step in the synthesis is an Ullmann [35,38] homo-coupling of iodo compound 3 to form the central C-C bond in 4. This reaction is highly selective and proceeds smoothly under relatively mild conditions in ...

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“…; Fp 2 320°C, Zers.). Elementaranalyse und J=7.8 und 4.7 Hz,2 H ;3,8.44 und 8.49 (AB,J=8.4 Hz,je 2 H ;5,8.59 (s,2 H ;7,9.15 (dd,J=8.0 und 1.6 Hz,2 H ;4,9.59 (dd,5=4.6 und 1.6 Hz,2H;2, …”

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Benzo[1,2‐h:4,3‐h′]dichinolin („1,14‐Diaza[5]helicen”︁): Synthese, Struktur und Eigenschaften

1989

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Trotz nahezu gleicher N ⃛N‐Abstände in 1 und 2 (272.8 bzw. 270.5 pm) ist die Basizitätskonstante von 2 um fast zwei Zehnerpotenzen geringer als die von 1. Ursache dürfte die helicale Struktur von 2 sein, die für die freie Base die destabilisierende „lone‐pair”︁‐Wechselwirkung der N‐Atome nahezu aufhebt und für 2a eine N ⃛H ⃛N‐Brücke entlang der Vorzugsrichtungen der „lone pairs”︁ der N‐Atome verhindert.

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4,5‐Bis(dimethylamino)phenanthren und 4,5‐Bis(dimethylamino)‐9,10‐dihydrophenanthren: Synthesen und „Protonenschwamm”︁‐Eigenschaften

Cited by 30 publications

References 10 publications

Strong Organic Bases as Building Blocks of Mesoporous Hybrid Catalysts for C–C Forming Bond Reactions

Strong Organic Bases as Building Blocks of Mesoporous Hybrid Catalysts for C–C Forming Bond Reactions

Synthesis of 6,6′‐Bis(dimethylamino)‐ and 6,6′‐Dibromo‐Substituted 2,2′‐Diphosphanylbiphenyls and Their Palladium Complexes

Benzo[1,2‐h:4,3‐h′]dichinolin („1,14‐Diaza[5]helicen”︁): Synthese, Struktur und Eigenschaften

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