+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Homogeneous catalysts supported on soluble polymers: biphasic Sonogashira coupling of aryl halides and acetylenes using MeOPEG-bound phosphine-palladium catalysts for efficient catalyst recycling



Homogeneous catalysts supported on soluble polymers: biphasic Sonogashira coupling of aryl halides and acetylenes using MeOPEG-bound phosphine-palladium catalysts for efficient catalyst recycling



Chemistry 9(6): 1416-1425



The Sonogashira coupling of various aryl bromides and iodides with different acetylenes was studied under biphasic conditions with soluble, polymer-modified catalysts to allow the efficient recycling of the homogeneous catalyst. For this purpose, several sterically demanding and electron-rich phosphines of the type R(P)PR(2) were synthesised. They are covalently linked to a monomethyl polyethylene glycol ether with a mass of 2000 Dalton (R(P)=MeOPEG(2000)) R(P)PR(2): -PR(2)= -CH(2)C(6)H(4)CH(2)P(1-Ad)(2), -C(6)H(4)-P(1-Ad)(2), -C(6)H(4)-PPh(2). To couple aryl iodides and acetylenes, the catalyst [(MeCN)(2)PdCl(2)]/2 R(P)-C(6)H(4)-PPh(2) was used in CH(3)CN/Et(3)N/n-heptane (5/2/5). The combined yields of coupling product over five reaction cycles are between 80-95 percent. There is no apparent leaching of the catalyst into n-heptane, as evidenced by (1)H NMR spectroscopy. The new catalyst [(MeCN)(2)PdCl(2)]/2 (1-Ad)(2)PBn can be used for room-temperature coupling of various aryl bromides and acetylenes in THF with HNiPr(2) as a base. A closely related catalyst Na(2)[PdCl(4)]/2 R(P)-CH(2)C(6)H(4)CH(2)P(1-Ad)(2) linked to the polymer was used to couple aryl bromides and acetylenes in DMSO or DMSO/n-heptane at 60 degrees C with 0.5 mol percent Na(2)[PdCl(4)], 1 mol percent R(P)PR(2) and 0.33 mol percent CuI. The combined yield of coupling products over five cycles is always greater than 90 percent, except for sterically hindered aryl bromides. The determination of the turnover frequency (TOF) of the catalyst indicates only a small decrease in activity over five cycles. Leaching of the catalyst into the product containing n-heptane solution could not be detected by means of (1)H NMR and TXRF; this is indicative of >99.995 percent catalyst retention in the DMSO solvent.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 049237211

Download citation: RISBibTeXText

PMID: 12645031

DOI: 10.1002/chem.200390161


Related references

Homogeneous catalysts supported on soluble polymers: biphasic Suzuki-Miyaura coupling of aryl chlorides using phase-tagged palladium-phosphine catalysts. Chemistry 10(7): 1789-1797, 2004

Comparison of palladium carbene and palladium phosphine catalysts for catalytic coupling reactions of aryl halides. Journal of Molecular Catalysis A: Chemical 214(2): 231-239, 2004

Nanocrystalline Magnesium Oxide Stabilized Palladium(0): An Efficient Heterogeneous Catalyst for Heck and Sonogashira Coupling of Aryl Halides. Synlett 2006(17): 2747-2750, 2006

Recycling of homogeneous Pd catalysts using superparamagnetic nanoparticles as novel soluble supports for Suzuki, Heck, and Sonogashira cross-coupling reactions. Chemical Communications 2005(35): 4435-4437, 2005

The development of efficient catalysts for palladium-catalyzed coupling reactions of aryl halides. Chemical Communications 2005(4): 431-440, 2005

Highly efficient and stable palladium/imidazolium salt-phosphine catalysts for SuzukiMiyaura cross-coupling of aryl bromides. Journal of Molecular Catalysis A: Chemical 259(1-2): 7-10, 2006

Nano palladium supported on high-surface-area metal-organic framework MIL-101: an efficient catalyst for Sonogashira coupling of aryl and heteroaryl bromides with alkynes. Applied Organometallic Chemistry 29(4): 234-239, 2015

A very efficient, copper-free palladium catalyst for the Sonogashira reaction with aryl halides. Chemical Communications 2003(15): 1934-1935, 2003

Highly active palladium catalysts supported by bulky proazaphosphatrane ligands for Stille cross-coupling: coupling of aryl and vinyl chlorides, room temperature coupling of aryl bromides, coupling of aryl triflates, and synthesis of sterically hindered biaryls. Journal of the American Chemical Society 126(50): 16433-9, 2004

Superparamagnetic nanoparticles-supported phosphine-free palladium catalyst for the Sonogashira coupling reaction. Journal of Molecular Catalysis A: Chemical 334(1-2): 130-138, 2011

A study on applications of N-substituted main-chain NHC-palladium polymers as recyclable self-supported catalysts for the Suzuki-Miyaura coupling of aryl chlorides in water. Inorganic Chemistry 50(13): 6063-6072, 2011

Computed ligand effects on the oxidative addition of phenyl halides to phosphine supported palladium(0) catalysts. Dalton Transactions 43(36): 13545-13556, 2014

The first heterogeneous Sonogashira coupling reaction of aryl halides with terminal alkynes catalyzed by diatomite-supported palladium(II) salophen complex. Applied Organometallic Chemistry 25(6): 420-423, 2011

Palladium-ADC complexes as efficient catalysts in copper-free and room temperature Sonogashira coupling. Journal of Molecular Catalysis A: Chemical 395: 162-171, 2014

Carbon dioxide pressure induced heterogeneous and homogeneous Heck and Sonogashira coupling reactions using fluorinated palladium complex catalysts. Journal of Supercritical Fluids 51(2): 209-216, 2009