Multifaceted Palladium Catalysts Towards the Tandem Diboration-Arylation Reactions of Alkenes

• Published in: Chemistry : a European journal 2008-11, Vol.14 (34), p.10648-10655
• Main Authors: Penno, Dirk, Lillo, Vanesa, Koshevoy, Igor O., Sanaú, Mercedes, Ubeda, M. Angeles, Lahuerta, Pascual, Fernández, Elena
• Format: Article
• Language: English
• Subjects: Alcohols - chemical synthesis; Alcohols - chemistry; Alkenes - chemistry; Boronic Acids - chemistry; Catalysis; chemoselectivity; cross-coupling; Crystallography, X-Ray; diboration; Models, Molecular; Molecular Structure; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; palladium; Palladium - chemistry; Particle Size; Stereoisomerism; tandem reactions; Time Factors
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200800931

Novel Pd26+ compounds have been synthesized in high yield. These compounds and their Pd24+ counterparts as synthetic precursors mediate the diboration of vinylarenes and aliphatic 1‐alkenes, and under mild and basic reaction conditions they produce a variety of 1,2‐diboronate esters with excellent conversions and chemoselectivities. The presence of bis(catecholato)diboron (B2cat2) favours the reduction of PdIII to PdII, while the catalytic precursor of PdII is transformed into Pd0‐nanoparticles. An “in situ” catalytic tandem reaction has been designed to transform the diboronate intermediates into the monoarylated product, which after oxidative workup, provides the carbohydroxylated adduct. Eventually, the same catalyst performs both sequences with total conversion from the alkene. Go tandem! Pd26+ and Pd24+ complexes were synthesized and used in the Pd‐mediated diboration of alkenes to produce a variety of 1,2‐diboronate esters with excellent conversions and chemoselectivities. The tetranuclear complex [Pd(C6H4PPh2)X]4 efficiently catalysed the tandem diboration–arylation reactions of the alkenes (see scheme).