Rhodium/Chiral Diene-Catalyzed Asymmetric Cyclopolymerization of Achiral 1,8-Diynes

Ichikawa, Yoshitaka; Nishimura, Takahiro; Hayashi, Tamio

doi:10.1021/om200088q

Cited by 25 publications

(13 citation statements)

References 70 publications

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“…120-122°C; 1 H NMR (700 MHz, CDCl 3 , 298 K): δ = 2.88 (s, 3H), 7.81 (t, J = 7.5 Hz, 1H), 7.90 (t, J = 7.6 Hz, 1H), 8.27 (d, J = 8.1 Hz, 1H), 9.01 (s, 1H), 9.07 (d, J = 8.1 Hz, 1H), 9.52 (s, 1H) ppm; 13 C NMR (176 MHz, CDCl 3 , 298 K): δ = 22.4, 123.5, 124.7, 128.2, 129.6, 130.6, 135.4, 141.4, 146.0, 148.6, 153.9, 155.2 7-Methoxy-2-methylquinoxaline (11). 37 To a solution of 5 (0.68 mmol, 99 mg, 1 equiv.) was added 3 M hydrochloric acid solution (30 equiv.).…”

Section: Experimental Partmentioning

confidence: 99%

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Synthesis of quinoxalines or quinolin-8-amines from N-propargyl aniline derivatives employing tin and indium chlorides

2015

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Pyrazino compounds such as quinoxalines are 1,4-diazines with widespread occurrence in nature. Quinolin-8-amines are isomerically related and valuable scaffolds in organic synthesis. Herein, we present intramolecular main group metal Lewis acid catalyzed formal hydroamination as well as hydroarylation methodology using mono-propargylated aromatic ortho-diamines. The annulations can be conducted utilizing equal aerobic conditions with either stannic chloride or indium(iii) chloride and represent primary examples for main group metal catalyzed 6-exo-dig and 6-endo-dig, respectively, cyclizations in such settings. Both types of reactions can also be utilized in a one-pot manner starting from ortho-nitro N-propargyl anilines using stoichiometric amounts SnCl2·2H2O or In powder. Mechanistic considerations are presented regarding the substituent-depending regioselectivity.

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Section: Experimental Partmentioning

confidence: 99%

“…Prepared in analogy to literature. 37 To a solution of 5 (0.68 mmol, 99 mg, 1 equiv.) in 4 ml acetonitrile were added 1-iodo-4methylbenzene (0.75 mmol, 165 mg, 1.1 equiv.…”

Section: Experimental Partmentioning

confidence: 99%

Synthesis of quinoxalines or quinolin-8-amines from N-propargyl aniline derivatives employing tin and indium chlorides

2015

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“…34−37 There is one report on Rhcatalyzed diyne cyclopolymerization, which gives a widebandgap polyene containing seven-membered rings via an insertion mechanism, but it yielded low molecular weight polymers with a maximum number-average molecular weight (M n ) of 6.5 kDa due to its poor efficiency. 38,39 This led us to wonder if 1,8-nonadiynes could be cyclopolymerized using Grubbs catalysts to prepare conjugated polyenes containing seven-membered rings via selective α-addition (Scheme 1c). Although the CP of 1,8-nonadiynes is expected to be even more challenging 40 than that of 1,7-octadiynes, rational and novel design of the monomers would lead to their successful CP.…”

Section: ■ Introductionmentioning

confidence: 99%

Seven-Membered Ring-Forming Cyclopolymerization of 1,8-Nonadiyne Derivatives Using Grubbs Catalysts: Rational Design of Monomers and Insights into the Mechanism for Olefin Metathesis Polymerizations

Song

Choi

2017

Macromolecules

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Studies into the cyclopolymerization (CP) of diyne derivatives using metal carbenes have focused on the formation of five- and six-membered rings because these small rings can be easily synthesized while the preparation of medium-sized seven-membered rings are more difficult. For the first time, we achieved the CP forming challenging seven-membered rings as repeat units using Grubbs catalysts by novel design of 1,8-nonadiyne monomers. The key to the successful CP was the introduction of the appropriate aminal and acetal groups, which have short C–N and C–O bonds, and low rotational barriers, thus greatly enhancing the cyclization efficiency. During our mechanistic investigation, we directly observed an actual 14-electron Ru propagating carbene by 1H NMR spectroscopy for the first time during olefin metathesis reaction, presumably because the great steric hindrance from the propagating carbene containing a larger seven-membered ring than five- or six-membered ring retarded the coordination of ligands. We also observed decomposition of the catalysts to ruthenium hydrides during polymerization for the first time. Kinetic studies revealed three interesting features of this 1,8-nonadiyne CP: (i) in contrast to conventional polymerizations, the rate-determining step for the CP of 1,8-nonadiynes was the cyclization step; (ii) the intrinsic reactivity of the acetal monomers was higher than that of the aminal monomers; but (iii) the overall polymerization efficiency of the aminal monomers was higher than that of the acetal monomers because of the higher stability of their carbenes. Finally, we achieved a controlled CP of the aminal monomers using a fast-initiating third-generation Grubbs catalyst. This allowed the synthesis of not only the diblock copolymer containing five- and seven-membered rings but also the triblock copolymer containing five-, six-, and seven-membered rings.

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“…Transition-metal catalysts polymerize various acetylene monomers to yield substituted polyacetylenes with useful functions, such as electro-active and photoluminescent properties, as a result of their conjugated main chains, their high gas permeability, and the helix-forming ability of their rigid backbones. [1][2][3][4][5] Well-defined transition-metal catalysts that contain tantalum, [6] molybdenum, [7][8][9] ruthenium, [10][11][12][13][14] rhodium, [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] nickel, [32] and palladium [33][34][35][36][37][38][39][40] are especially useful for acetylene polymerization, because they allow control over catalytic activity by judicious ligand design, thereby enabling living/controlled polymerization. As a result, precise modification of the polymer architectures are achieved, which enable the synthesis of block copolymers and starshaped polymers.…”

Section: Introductionmentioning

confidence: 99%

“…[41] Among these transition-metal catalysts for acetylene polymerization mentioned above, Rh-and Pd-based compounds catalyze the polymerization of acetylene monomers that are substituted with heteroatom-containing polar groups, as well as nonpolar hydrocarbon acetylene monomers, owing to the low oxophilicity of late transition metals. Although Rhbased catalysts [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] have been widely studied and utilized to obtain cis-stereoregular-substituted polyacetylenes, Pd-based catalysts [32][33][34][35][36][37][38][39][40] have not been extensively examined for acetylene polymerization, presumably owing to their lower activity compared with that of Rh catalysts. Darkwa, Pollack and co-workers have developed well-defined [(diphosphine)Pd-A C H T U N G T R E N N U N G (NCCH 3 )A C H T U N G T R E N N U N G (CH 3 )]OTf-type catalysts and successfully polymerized phenylacetylene (PA) to obtain poly(PA)s with moderate molecular weights in good yields.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of End‐Functionalized Polyacetylenes that Contain Polar Groups by Employing Well‐Defined Palladium Catalysts

Castanon

Kuwata

Shiotsuki

et al. 2012

Chemistry A European J

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A series of [(dppf)PdBr(R)]-type complexes (dppf=1,1'-bis(diphenylphosphino)ferrocene; R=p-cyanophenyl (1 a), o-hydroxymethylphenyl (1 b), and triphenylvinyl (1 c)), in combination with silver trifluoromethanesulfonate (AgOTf), were demonstrated to be active for the polymerization of monosubstituted polar acetylene monomers HC≡CCONHC(4)H(9) (2), HC≡CCO(2)C(8)H(17) (3), HC≡CCH(2)OCONHC(6)H(13) (4), HC≡CCH(2)OCO(2)C(6)H(13) (5), and HC≡CCH(CH(3))OH (6). The yields and molecular weights of the polymers depended on the combination of the Pd catalyst and monomer that was employed. Matrix-assisted laser-desorption/ionization-time of flight (MALDI-TOF) mass spectrometric analysis indicated the formation of polymers that contained the "R" and "H" groups at the chain ends. IR spectroscopic analysis supported the R-end-functionalization of the polymers. NMR spectroscopy and MS identified the presence of species that were formed by single, double, and triple insertion of the monomers into the Pd-C(6)H(4)-p-CN bond, thereby giving solid evidence for an insertion mechanism for the present system. Density functional theory (DFT) calculations suggested the preference for 1,2-insertion of the monomer compared to 2,1-insertion.

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Rhodium/Chiral Diene-Catalyzed Asymmetric Cyclopolymerization of Achiral 1,8-Diynes

Cited by 25 publications

References 70 publications

Synthesis of quinoxalines or quinolin-8-amines from N-propargyl aniline derivatives employing tin and indium chlorides

Synthesis of quinoxalines or quinolin-8-amines from N-propargyl aniline derivatives employing tin and indium chlorides

Seven-Membered Ring-Forming Cyclopolymerization of 1,8-Nonadiyne Derivatives Using Grubbs Catalysts: Rational Design of Monomers and Insights into the Mechanism for Olefin Metathesis Polymerizations

Synthesis of End‐Functionalized Polyacetylenes that Contain Polar Groups by Employing Well‐Defined Palladium Catalysts

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