Michael and Acetal Aldol-Type Reactions on Solid-Phase. Use of the Swollen- Resin Magic Angle Spinning (SR-MAS) NMR Technique for the Development of the Solid-Phase Organic Reactions

Kobayashi, Shū; Akiyama, Ryo; Furuta, Takayuki; Moriwaki, Mitsuhiro

doi:10.1007/s007830050052

Cited by 31 publications

(31 citation statements)

References 14 publications

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“…The resulting resin was treated with NaOMe at room temperature for 1 h in THF to afford the desired α-amino acid derivative (4) in 76% yield. When ytterbium trifluoromethanesulfonate [ytterbium triflate; Yb(OTf) 3 ] was used as a catalyst, the yield was slightly reduced. Various types of silyl enolates derived from esters as well as thioesters and ketones reacted smoothly to afford the corresponding α-amino acid derivatives, which are an interesting class of biologically important compounds.…”

Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

“…In the presence of 20 mol % Sc(OTf) 3 , 3a reacted with dihydrofuran at room temperature for 20 h in CH 2 Cl 2 -CH 3 CN (1:1) to give 2-methoxycarbonyltetrahydroquinoline derivative in 72% yield after cleavage from the polymer support. Other examples are examined, and in all cases the desired reactions proceeded smoothly in the solid-phase to afford the corresponding tetrahydroquinoline derivatives in good to excellent yields.…”

Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

“…The reaction of 2 with p-anisidine was found to proceed smoothly at room temperature in DMF to give 2-(4'-methoxyphenyl)iminoacetate resin (3a) quantitatively. In these transformations in the solid-phase, 13 C swollen-resin magic-angle spinning NMR (SR-MAS NMR) analysis [3] provided a powerful tool to optimize the reaction conditions of each step and to determine the structures of these resins (1, 2, and 3a) (Fig. 2).…”

Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

“…In the presence of 20 mol % scandium trifluoromethanesulfonate [scandium triflate; Sc(OTf) 3 ], 3a was treated with the silyl enolate derived from methyl isobutyrate at room temperature for 20 h in CH 2 Cl 2 -CH 3 CN (1:1). The resulting resin was treated with NaOMe at room temperature for 1 h in THF to afford the desired α-amino acid derivative (4) in 76% yield.…”

Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

“…We have immobilized alkyl glyoxylate equivalents onto resins and prepared novel polymer-supported imines. We have also developed unprecedented polymer-supported catalysts such as microencapsulated scandium trifluoromethanesulfonate [MC Sc(OTf) 3 ], osmium tetroxide (MC OsO 4 ), and palladium triphenylphosphine [MC Pd(PPh 3 )] for high-throughput synthesis. …”

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New methods for high-throughput synthesis

Kobayashi

Akiyama

2001

Pure and Applied Chemistry

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New methodologies for library synthesis have been developed. They are based on new carbon-carbon bond-formation reactions in the solid-phase and organic synthesis using polymer-supported catalysts. We have immobilized alkyl glyoxylate equivalents onto resins and prepared novel polymer-supported imines. We have also developed unprecedented polymer-supported catalysts such as microencapsulated scandium trifluoromethanesulfonate [MC Sc(OTf) 3 ], osmium tetroxide (MC OsO 4 ), and palladium triphenylphosphine [MC Pd(PPh 3 )] for high-throughput synthesis.

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Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

Section: Organic Synthesis On Solid Supportsmentioning

confidence: 99%

mentioning

confidence: 99%

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New methods for high-throughput synthesis

Kobayashi

Akiyama

2001

Pure and Applied Chemistry

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Ein neuartiger, in Wasser hoch aktiver polymergebundener Scandiumkatalysator

Nagayama

Kobayashi²

2000

Angewandte Chemie

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Die polymergebundenen Lewis‐Säuren 1 wurden erstmals als in Wasser aktive Katalysatoren eingesetzt. Die katalytische Aktivität, die nicht auf die Gegenwart eines organischen Lösungsmittels angewiesen ist, wurde zunächst anhand der Allylierung mit Tetraallylzinn untersucht, kann aber auch in anderen Lewis‐Säure‐katalysierten Reaktionen von Carbonylverbindungen wie aromatischen, aliphatischen und heterocyclischen Aldehyden und auch Ketonen zu den entsprechenden Alkoholen genutzt werden. Durch einfache Filtration kann der Katalysator dabei quantativ zurückgewonnen werden.

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Microencapsulated Palladium Catalysts: Allylic Substitution and Suzuki Coupling Using a Recoverable and Reusable Polymer-Supported Palladium Catalyst

Akiyama

Kobayashi

2001

Angew. Chem.

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While palladium catalysts find wide-spread utility in a variety of transformations in organic synthesis, [1] they are expensive, air-sensitive, and cannot be recovered in many cases. Immobilized palladium catalysts have been expected to solve these problems, and several polymer-supported palladium catalysts have been developed for allylic substitution, [2, 9a,b,e] oligomerization, [2c, 3, 4] decarboxylation, [2d] hydrogenation, [4, 9g] isomerization, [5] telomerization, [6] Suzuki coupling, [7, 9c,d,h] and the Mizoroki ± Heck reaction, [4c, 8, 9f,h] etc. In most of these cases, however, recovery and reuse of the polymer catalysts have not been satisfactory. [9] Recently, we developed novel polymer-supported catalysts, microencapsulated scandium trifluoromethanesulfonate (MC Sc(OTf) 3 ) [10] and osmium tetroxide (MC OsO 4 ). [11] Our work has demonstrated a new method for immobilizing catalysts onto polymers based on physical envelopment by the polymers and on electronic interaction between the p electrons of the benzene rings of the polystyrene-based polymers and vacant orbitals of the catalysts. We now apply this new technology to immobilizing palladium catalysts. Herein, we describe the use of microencapsulated triphenylphosphane palladium for allylic substitution and Suzuki coupling. In both cases, the catalysts were recovered quantitatively and reused. Moreover, valuable information on the structure of microencapsulated catalysts was obtained.Preparation of microencapsulated triphenylphosphane palladium was as follows: [12] polystyrene (1.0 g, M w ca. 280 000) was dissolved in cyclohexane (20 mL) at 40 8C, and to this solution was added tetrakis(triphenylphosphane)palladium(0) ([Pd(PPh 3 ) 4 ] 0.20 g) as a core ([Pd(PPh 3 ) 4 ] was dissolved). The mixture was stirred for 1 h at this temperature (and changed from brown to black), then slowly cooled to 0 8C. Coacervates (phase separation) were found to envelop the core dispersed in the medium, and hexane (30 mL) was added to harden the capsule walls. The mixture was left to stand at room temperature for 12 h, and the catalyst capsules were then washed with acetonitrile several times and dried at room temperature for 24 h. Three equivalents of triphenylphosphane (PPh 3 ) were recovered from the washings and one equivalent of PPh 3 remained in the catalyst capsules. We measured 31 P swollen-resin magic angle spinning (SR-MAS) trations a second by-product (`5 %) could be observed, which is most likely attributable to a square. The solvent was removed under a stream of N 2 , and the resulting white precipitate was dried in vacuo (yield 93 %). 1 H NMR (CD 3 NO 2 , 300 MHz): d 9.41 (s, 2 H; H pyr ), 1.79 (d, J P,H 11.4 Hz, 9 H; P-CH 3 ); 31 P{ 1 H} NMR (CD 3 NO 2 , 121 MHz): d À 25.6 (s, 195 Pt satellites, J Pt,P 3269 Hz); 19 F NMR (CD 3 NO 2 , 282 MHz): d À 78.1; 13 C{ 1 H} NMR (CD 3 NO 2 , 75 MHz): d 151.8 (s, C pyr ), 122.2 (q, J C,F 319 Hz, OTf), 14.7 (m,P-CH 3 ).

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Michael and Acetal Aldol-Type Reactions on Solid-Phase. Use of the Swollen- Resin Magic Angle Spinning (SR-MAS) NMR Technique for the Development of the Solid-Phase Organic Reactions

Cited by 31 publications

References 14 publications

New methods for high-throughput synthesis

New methods for high-throughput synthesis

Ein neuartiger, in Wasser hoch aktiver polymergebundener Scandiumkatalysator

Microencapsulated Palladium Catalysts: Allylic Substitution and Suzuki Coupling Using a Recoverable and Reusable Polymer-Supported Palladium Catalyst

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