Dehydrogenative Bond-Forming Catalysis Involving Phosphines: Updated Through 2010

Abstract

This updated version of a 2008 review presents work in the still developing field of dehydrogenative coupling reactions of phosphines. Catalytic phosphorus-element bond formation via dehydrocoupling has rapidly expanded since the first discoveries in the mid 1990s. A survey of the available catalysts, P-P and P-E products, and mechanistic understanding is presented with emphasis on the emerging synthetic applications of this reaction.

Evidence for Iron‐Catalyzed α‐Phosphinidene Elimination with Phenylphosphine

“…Additionally, two unusual products for dehydrocoupling catalysis, a triphosphine, (PhPH) 2 PPh, and Ph 2 PH, were observed in 6 and 1 % conversion, respectively, by 31 P NMR spectroscopy . The reliable formation of (PhPH) 2 PPh is unknown in catalytic dehydrocoupling reactions of PhPH 2 , and Ph 2 PH was also observed in Layfield's recent report on catalytic phosphinidene transfer . These two products, the triphosphine and diphenylphosphine, hint at α‐phosphinidene elimination, which prompted attempts to trap such putative fragments with unsaturated substrates.…”

“…For example, treatment of phenylphosphine with 10 mol % of 1 at 65 °C in a benzene/Et 2 O 1:9 solution gave hydrogen and primarily (PhPH) 2 in approximately 45 % conversion, as was observed by 31 P NMR spectroscopy . Additionally, two unusual products for dehydrocoupling catalysis, a triphosphine, (PhPH) 2 PPh, and Ph 2 PH, were observed in 6 and 1 % conversion, respectively, by 31 P NMR spectroscopy . The reliable formation of (PhPH) 2 PPh is unknown in catalytic dehydrocoupling reactions of PhPH 2 , and Ph 2 PH was also observed in Layfield's recent report on catalytic phosphinidene transfer .…”

Terminal Phosphanido Rhodium Complexes Mediating Catalytic PP and PC Bond Formation

“…[5] Moreover, safety, selectivity and 'green synthesis' are major advantages of dehydrocoupling and hydrophosphination catalysis. [6] Consequently, the formation of PC and PP bonds using these methodologies has attracted considerable attention, intensified by the possibility of activate the resulting PP bonds for the synthesis of new phosphorusbased derivatives. [ 7 ] Prevailing catalysts for dehydrogenative PP coupling are zirconium and titanium complexes, [8] while the viability of late transition metal compounds in this field remains almost unknown with two notable examples in rhodium chemistry described below.…”

Terminal Phosphanido Rhodium Complexes Mediating Catalytic PP and PC Bond Formation

“…[5] Moreover, safety, selectivity, and "green synthesis" are major advantages of dehydrocoupling and hydrophosphination catalysis. [6] Consequently, the formation of PÀC and PÀP bonds using these methods has attracted considerable attention, intensified by the possibility of activating the resulting P À P bonds for the synthesis of new phosphorus-based derivatives.…”