Phosphine-pyridonate ligands containing octahedral ruthenium complexes: access to esters and formic acid

Abstract

Selective formation of esters from primary alcohols or formic acid from carbon dioxide was achieved in the presence of phosphine-pyridone containing ruthenium catalysts.

Direct Access to (±)‐10‐Desbromoarborescidine A from Tryptamine and Pentane‐1,5‐diol

“…GC/MS analyses indicated the side formation of the (±)‐10‐desbromoarborescidine A ( 4 ) and the N ‐monoalkylated tryptamine, thus confirming our working hypothesis . Astonishingly, our ruthenium precatalyst Ru‐1 containing phosphine‐pyridone ligand under similar reaction conditions led to complete conversion of the tryptamine 1 a again with the major formation of the tricyclic product 3 along with 4 as the only side product in an interesting 7 : 3 ratio (entry 7) . It should be mentioned that under refluxing conditions with a Schlenk tube equipped with a condenser and a bubbler, in the presence of precatalyst Ru‐1 , product 3 can be more selectively obtained with complete conversion and a 9 : 1 ratio (entry 8).…”

“…In 2005, Williams and coworkers, reported the N ‐alkylation of tryptamine with pentane‐1,5‐diols leading to the selective formation of N ‐heterocycles without formation of the indoloquinolizidine Pictet‐Spengler adduct . Based on our recent contributions on tandem hydrogen transfer processes for the synthesis and functionalization of aza‐heterocycles, we postulated that our recent Ru‐1 precatalyst (Scheme ) would enable N ‐alkylation and be acidic enough to play the role of Pictet‐Spengler surrogate to efficiently afford indoloquinolizidine in one step generating hydrogen and water as the only side products of the transformation (Scheme ) …”

Photocatalytic Dehydrogenation of Formic Acid on CdS Nanorods through Ni and Co Redox Mediation under Mild Conditions

“…The notable exceptions are the examples of iron catalyst systems capable of dehydrogenating FA‐to‐H 2 in acidic media, exhibiting catalytic activities comparable to the noble metal catalysts . In addition, the catalytic activity and selectivity are enhanced employing additional base and/or additives . Despite the substantial progress, the inherent separation workup and recycling issues of homogeneous catalytic systems, harsh operating conditions and selectivity, and the requirement of additives may stymie their practical realization in device fabrication .…”

Catalyst Design for Highly Efficient Base-Free Carbon Dioxide Hydrogenation to Formic Acid

“…In this regard DMSO has found increased attention. [40][41][42] Here the basic properties of the solvent are exploited to stabilize the product by hydrogen bonding 41 and can be further enhanced by the addition of small amounts of water. 40 Furthermore, water [43][44][45] and ionic liquids (ILs) [46][47][48] have demonstrated to facilitate the formation of FA from CO2 and H2.…”

“…However, in most cases the catalytic turnover [41][42] and concentrations of FA obtained [43][44][45] are relatively modest, with TONs<1000. Very recently, we have reported that ionic liquids can efficiently mediate the hydrogenation of CO2 to formic acid by acting as a buffer.…”