ABSTRACT
Described herein are newly developed, straightforward entries to polyethyleneglycol ubiquinol succinate (PQS, n = 2), a designer surfactant that serves as precursor to micelle-forming, covalently bound catalysts for a variety of transformations in water with in-flask catalyst recycling.
Subject(s)
Organic Chemicals/chemistry , Polyethylene Glycols/chemistry , Polyethylene Glycols/chemical synthesis , Solvents/chemistry , Succinates/chemistry , Succinates/chemical synthesis , Surface-Active Agents/chemistry , Surface-Active Agents/chemical synthesis , Water/chemistry , Catalysis , Micelles , Molecular Structure , SolubilityABSTRACT
Using the newly introduced designer surfactant polyethyleneglycol ubiquinol sebacate (PQS), as the platform for micellar catalysis, nonracemic BINAP has been covalently attached and rhodium(I) inserted to form PQS-BINAP-Rh. This species, the first example of a nonracemically-ligated transition metal catalyst-tethered amphiphile, can be utilized for Rh-catalyzed asymmetric conjugate addition reactions of arylboronic acids to acyclic and cyclic enones. These are performed in water at room temperature, while the catalyst can be recycled without its removal from water in the reaction vessel.
ABSTRACT
An environmentally benign surfactant (TPGS-750-M), a diester composed of racemic α-tocopherol, MPEG-750, and succinic acid, has been designed and readily prepared as an effective nanomicelle-forming species for general use in metal-catalyzed cross-coupling reactions in water. Several "name" reactions, including Heck, Suzuki-Miyaura, Sonogashira, and Negishi-like couplings, have been studied using this technology, as have aminations, C-H activations, and olefin metathesis reactions. Physical data in the form of DLS and cryo-TEM measurements suggest that particle size and shape are key elements in achieving high levels of conversion and, hence, good isolated yields of products. This new amphiphile will soon be commercially available.
Subject(s)
Metals/chemistry , Succinates/chemistry , Temperature , Vitamin E/analogs & derivatives , Water/chemistry , Catalysis , Hydrophobic and Hydrophilic Interactions , Micelles , Polyethylene Glycols , Sulfonamides/chemistry , Surface-Active Agents/chemistry , Thiadiazoles/chemistry , Vitamin E/chemistryABSTRACT
The first study on a general technology for arriving at valued nonracemic allylic alcohols using asymmetric ligand-accelerated catalysis by copper hydride is described.
Subject(s)
Coordination Complexes/chemistry , Ketones/chemistry , Alcohols/chemistry , Catalysis , Oxidation-Reduction , Stereoisomerism , Substrate SpecificityABSTRACT
Allylic phenyl ethers serve as electrophiles toward Pd(0) en route to a variety of allylic silanes. The reactions can be run at room temperature in water as the only medium using micellar catalysis.
Subject(s)
Allyl Compounds/chemical synthesis , Ethers/chemistry , Palladium/chemistry , Phenyl Ethers/chemical synthesis , Silanes/chemical synthesis , Allyl Compounds/chemistry , Catalysis , Combinatorial Chemistry Techniques , Molecular Structure , Phenyl Ethers/chemistry , Silanes/chemistry , StereoisomerismABSTRACT
New technology for palladium-catalyzed cross-couplings between B2pin2 and aryl bromides leading to arylboronates is described. Micellar catalysis serves to enable borylations to take place in water as the only medium at ambient temperatures.
ABSTRACT
A full account of a recently discovered gold(I)-catalyzed reaction, a cycloaddition of carbonyl compounds to enynes yielding 2-oxabicyclo[3.1.0]hexanes with four stereogenic centers, is presented. The reaction proceeds with very high diastereoselectivity. The scope of the reaction has been investigated. In addition, experiments and DFT calculations concerning mechanistic aspects were carried out. The reaction course varies with the substitution pattern of the alkene moiety of the starting enyne. Branched olefins led to 2-oxabicyclo[3.1.0]hexanes; terminally substituted olefins proceeded with the incorporation of two carbonyl components to give hexahydrocyclopenta[d][1,3]dioxines.
