Regio‐ and Diastereoselective CC Coupling of α‐Olefins and Styrenes to 3‐Hydroxy‐2‐oxindoles by Ru‐Catalyzed Hydrohydroxyalkylation

Abstract

The direct approach: Ruthenium(0)‐catalyzed hydrohydroxyalkylation of α‐olefins and styrenes with 3‐hydroxy‐2‐oxindoles forms branched products of CC coupling with high levels of diastereocontrol. A mechanism involving diene–olefin oxidative coupling and a subsequent carboxylic acid co‐catalyzed transfer hydrogenolysis of the resulting oxaruthenacycle intermediate is postulated.

Ruthenium-Catalyzed Transfer Hydrogenation for C–C Bond Formation: Hydrohydroxyalkylation and Hydroaminoalkylation via Reactant Redox Pairs

“…In the absence of carboxylic acid cocatalyst, only trace quantities of product were formed (Scheme 13). 78 …”

Feedstock Reagents in Metal‐Catalyzed Carbonyl Reductive Coupling: Minimizing Preactivation for Efficiency in Target‐Oriented Synthesis

“…Isoprene oxide is obtained upon regioselective metal-cata-lyzed epoxidation of the feedstock diene isoprene (8 10 5 tons yr À1 ). [54] Styrene (2.5 10 7 tons yr À1 )i sa lso ac ompetent partner in these transformations,a nd in couplings with simple aliphatic alcohols (not shown). [52,53] Beyond alkanes,w hich are so plentiful they are used as fuel, the most abundant petrochemical feedstocks are ethylene (1.5 10 8 tons yr À1 )a nd higher olefins such as propylene (1.0 10 8 tons yr À1 )a nd 1-octene (1 10 6 tons yr À1 ).…”

Metal-catalyzed reductive coupling of olefin-derived nucleophiles: Reinventing carbonyl addition

“…The concept of transfer hydrogenative carbonyl addition introduced by our laboratory (8-10) provides an important inroad to this problem. Using ruthenium(0) catalysts, vicinally oxygenated secondary alcohols serve dually as reductants and carbonyl precursors (11, 12) (Figure 2). Ethylene, propylene, 1-octene, styrene and a host of other terminal olefins were found to engage in highly regio- and diastereoselective C-C coupling with 3-hydroxy-2-oxindoles to form the corresponding tertiary alcohols (11).…”

“…Using ruthenium(0) catalysts, vicinally oxygenated secondary alcohols serve dually as reductants and carbonyl precursors (11, 12) (Figure 2). Ethylene, propylene, 1-octene, styrene and a host of other terminal olefins were found to engage in highly regio- and diastereoselective C-C coupling with 3-hydroxy-2-oxindoles to form the corresponding tertiary alcohols (11). The scope of this process was extended through the use of related osmium(0) catalysts (12), which promote the C-C couplings of ethylene and 1-octene with diols, α-ketols or α-hydroxy esters by way of vicinal dicarbonyl intermediates.…”