Cross-coupling reactions monophosphine ligands

Air-stable biaryl monophosphine ligands developed by Buchwald and co-workers have played a central role in the advancement of palladium-catalyzed cross-coupling reactions, including BHA chemistry the utility of appropriately configured ancillary ligands of this type in the selective monoarylation of ammonia has been examined. Following on preliminary experimentation that established the capability of the Pd2(dba)j/L3 catalyst system (dba=dibenzylideneacetone) to promote the monoarylation of ammonia at elevated temperature Tsvelikhovsky... 

All ligands that make Pd complexes able to activate aryl bromides and chlorides in oxidative additions, such as palladacycles, NHC carbenes, bulky monophosphines, or polyphosphines, have also been successfully used for most cross-coupling reactions reported in the following that aU involve oxidative addition as the first step of the catalytic cycle [3h, k, 9,12d, 15e]. 

The Suzuki reaction of halo-pyrimidines with organoboron derivatives is not limited to Csp2—Csp2 coupling, but can also be accomplished in a Csp —( sp- fashion. Hydroboration of terminal alkene 107 with 9-BBN followed by Pd-catalyzed Suzuki cross coupling with 5-bromopyrimidine provides the desired alkyl substituted product 108. The classical Suzuki conditions proved insufficient, whereas the combination of Pd(OAc)2 and a biphenyl monophosphine ligand developed by Buchwald provided the desired product in 55% yield [45]. 

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