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Most Requested Journal Articles 2002-Chemistry and Related
 Following is one of the documents most requested by researchers using CAS electronic products.
CAPLUS COPYRIGHT 2003 ACS
ABSTRACT: Pentaphenylferrocenyl di-tert-butylphosphine I (R = R1 = Ph) was prepd.; the scope of various cross-coupling processes catalyzed by palladium complexes of I has been investigated. I (R = R1 = Ph) was prepd. by lithiation of ferrocene followed by removal of solvent, addn. of a 5:1 pentane:THF mixt., and addn. of di(tert-butyl)chlorophosphine to give mono(di-tert-butylphosphino)ferrocene with high chemoselectivity; arylation of the ferrocenylphosphine with chlorobenzene as a solvent in the presence of palladium (II) acetate and sodium tert-butoxide yielded I in 40-65% yield overall. I (R = R1 = Ph) acts as a highly effective ligand for palladium-catalyzed amination and for Suzuki coupling reactions with aryl- and alkylboronic acids. Unactivated, electron-rich, and electron-poor aryl bromides and chlorides undergo coupling reactions in the presence of palladium complexes of I (R = R1 = Ph) with high turnover nos. Aryl bromides were coupled to alcs. in the presence of I (R = R1 = Ph); silanols and electron-rich phenols were coupled to activated aryl halides in the presence of I (R = R1 = Ph). Intramol. coupling reactions of alcs. and aryl bromides were successful, although substrates with hydrogens .alpha. to the alc. oxygen underwent some .beta.-hydride elimination. Acyclic and cyclic primary and secondary alkyl- and arylamines underwent coupling reactions with aryl bromides and chlorides in the presence of I (R = R1 = Ph). Aryl- and primary alkylboronic acids underwent coupling reactions in the presence of I (R = R1 = Ph); coupling of alkylboronic acids with aryl halides was successful in the absence of toxic or expensive bases. Other substituted ferrocenylphosphines I (R = R1 = 4-MeOC6H4, 4-F3CC6H4) were prepd. but palladium catalysts derived from the ligands showed little difference in catalytic activity when compared to palladium catalysts derived from I (R = R1 = Ph). Palladium catalysts derived from I (R = R1 = 3,5-Me2C6H3) were active in coupling reactions with aryl halides and alcs. but not in amination or Suzuki coupling reactions; I (R = Ph; R1 = H) acted as a catalyst for coupling reactions but gave significantly decreased yields due to decreased steric hindrance of the reaction center in the palladium complexes. I (R = R1 = Ph) not only generates highly active palladium catalysts, but is also air stable both in soln. and in the solid state. Palladium(0) complexes of I (R = R1 = Ph) are air stable solids and react only slowly with oxygen in soln. Crystal structure of I (R = R1 = Ph; R = Ph; R1 = H) were detd. by X-ray crystallog. View the full-text pdf document from the American Chemical Society, a participating ChemPort publisher. Updated 5/4/2007 9:23:18 AM
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