67746-30-9Relevant articles and documents
In situ 1H-PHIP-NMR studies of the stereoselective hydrogenation of alkynes to (E)-alkenes catalyzed by a homogeneous [Cp*Ru]+ catalyst
Schleyer,Niessen,Bargon
, p. 423 - 426 (2007/10/03)
The hydrogenation of internal alkynes using a [Cp*Ru(alkene)]+ complex leads to the formation of (E)-alkenes. This ruthenium complex represents one of the few homogeneous catalysts that trans-hydrogenate internal alkynes directly and stereoselectively. We have studied its stereoselectivity by in situ PHIP-NMR spectroscopy (PHIP = para-hydrogen induced polarization). With this method the initially formed products can be identified and characterized even at very low concentrations and low conversions. Furthermore, their subsequent fate can be evaluated with high sensitivity and with time resolution. Different alkyne substrates were used to demonstrate the universal applicability of this catalyst. The catalyst is not active in combination with terminal alkynes, however, possibly due to the formation of a rather stable vinylidene complex. A mechanism proceeding via a binuclear complex is proposed to explain the formation of the (E)-alkenes.
Reactions with Phosphine Alkylenes, 44. A Further Synthesis of (Z)-α,β-Unsaturated Aldehydes
Bestmann, Hans Juergen,Ermann, Peter
, p. 3264 - 3266 (2007/10/02)
Reaction of phosphorus ylides 4, especially such with electron donating groups R, with the glyoxal semiacetal 5 leads Z-stereospecifically to the formation of the acetals 3, which can be cleaved to the (Z)-α,β-unsaturated aldehydes 6.
