Water-based reactions allylic substitution

The inverse temperature-dependent solubility in aqueous media of polymer-bound palladium(0)-phosphine catalysts, based on the water-soluble polymer poly(Wisopropyl)acrylamide (PNIPAM) 28, was also used to recycle and reuse these catalysts in nucleophilic allylic substitutions (Equation (8)) and cross-coupling reactions between aryl iodides and terminal alkynes (Equation (9)). The catalyst was highly active in both reactions, and it was recycled 10 times with an average yield of 93% in the allylic nucleophilic substitution by precipitation with hexane. ... 

An 5 n2 allylic substitution of l,3-diphenyl-2-propenyl acetate by the enamine nucleophile produced from ketones and aldehydes gives C -substituted aldehydes and ketones in moderate to high yields (60-95%) and high enantioselectivities (79-98% ee). The reaction requires the presence of a palladium catalyst, pyrrolidine, and water. The palladium catalyst was prepared from a chiral ferrocene P,N ligand when a ketone was used, but with a ruthenium-based P,P ligand when an aldehyde was used in the reaction. 

Palladium-catalyzed nucleophilic substitution of allylic substrates (Tsuji-Trost coupling) is a most important methodology in organic synthesis and therefore it is no wonder that such reactions have been developed also in aqueous systems. Carbo- and heteronucleophiles have been found to react with allylic acetates or carbonates in aqueous acetonitrile or DMSO, in water or in biphasic mixtures of the latter with butyronitrile or benzonitrile, affording the products of substitution in excellent yields (Scheme 6.19) [7-11,14,45,46], Generally, K2C03 or amines are used as additives, however in some cases the hindered strong base diazabicycloundecene (DBU) proved superior to other bases. 

AP (504-29-0) Reacts with water, forming a strong base. Violent reaction with strong oxidizers, strong acids, isopropyl percarbonate, nitrosyl perchlorate. Aqueous solutions incompatible with organic anhydrides, acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cresols, caprolactam solution, epichlorohydrin, ethylene dichloride, glycols, isocyanates, ketones, maleic anhydride, nitrates, nitromethane, phenols, vinyl acetate. APARASIN (58-89-9) see lindane. APAVINPHOS (7786-34-7) see MEVINPHOS . 

SODIUM ALUMINATE or SODIUM ALUMINATE SOLUTION (45% or less) or SODIUM ALUMINUM OXIDE (1302-42-7 1138-49-1) AlOj Na Noncombustible solid. Aqueous solution is a strong corrosive base. Violent exothermic reaction with acids. Incompatible with aluminum, organic anhydrides acrylates, alcohols, aldehydes, alkylene oxides, substituted allyls, cellulose nitrate, chlorocarbons, copper, cresols, caprolactam solution, chlorocarbons, epichlorohydrin, ethylene dichloride, isocyanates, ketones, glycols, nitrates, phenols, phosphoms, tin, vinyl acetate, zinc. Exothermic decomposition with maleic anhydride. May increase the explosive sensitivity of nitromethane. Attacks aluminum, copper, tin, and zinc. On small fires, use dry chemical powder (such as Purple-K-Powder), sand, or COj extinguishers. Avoid the use of water or foam. 

---