Allylic nucleophilic substitution

Example of Cyclopropanation, Diels-Alder Reaction, Nucleophilic Allylic Substitution... 

Chiral pyridine-based ligands were, among various Ar,AT-coordinating ligands, more efficient associated to palladium for asymmetric nucleophilic allylic substitution. Asymmetric molybdenum-catalyzed alkylations, especially of non-symmetric allylic derivatives as substrates, have been very efficiently performed with bis(pyridylamide) ligands. 

Keywords N,N-Containing ligands Asymmetric catalysis Cyclopropanation Diels-Alder reaction Nucleophilic allylic substitution... 

Asymmetric nucleophilic allylic substitution has rarely been studied in its heterogeneous version, probably because of the difficulties encoimtered in properly stabilizing and recycling Pd(0) species. Nevertheless, some promising examples have been pubhshed. Lemaire et al. [143] studied the activity and enantioselectivity of various chiral C2-diamines for the asymmetric Pd-catalyzed transformation of various allyl acetates. The structures tested are represented in Scheme 58. 

Pd-catalyzed nucleophilic allylic substitutions perform efficiently in an enan-tioselective way by using chiral phosphorous-containing ligands. Due to their high stability and convenient handling, M-containing ligands have recently... 

Schulz E (2005) Use of JV,JV-Coordinaling Ligands in Catalytic Asymmetric C-C Bond Formations Example of Cyclopropanation, Diels-Alder Reaction, Nucleophilic Allylic Substitution. 15 93-148... 

The synthetic methods for the preparation of allyl amines can be divided into several types of reactions [1]. In the present chaptgr, the focus will be on the formation of allyl amines by reaction of substrates having an allylic bond which can be broken. Two approaches will be covered and these are outlined in Scheme 1 the first method (a) is the synthesis of allyl amines by nucleophilic allylic substitution of compounds having an allyl functionality the second method (b) is the direct allylic amination of simple alkenes. 

New versatile Pd-catalyzed alkylation of indoles 523 via nucleophilic allylic substitution provides 3-allylindoles 524 in good to excellent yields (Scheme 107) <20040L3199 and references therein>. The regioselectivity of the reaction... 

The Pd-catalyzed C-3 alkylation of indoles via nucleophilic allylic substitution on allylic carbonates and acetates has been described [90]. Two clever indole ring syntheses involving oxidative cyclization are illustrated below [91]. 

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. ... 

Scheme 12.2 Mechanisms of the palladium-catalyzed nucleophilic allylic substitutions.

Focusing on benzene-like arenes, Shu-Li You described an efficient intramolecular Ir-catalyzed nucleophilic allylic substitution of phenols, addressing meto-substituted hydroxyarene with allylic carbonate side chains 31 as acyclic precursors [20]. A range of tetrahydroisoquinolines 33 was isolated in good yields (up to 90%) and ee up to 96% in the presence of chiral phosphoramidite ligand (5,5,5 )-32 (4mol%) and [IrCKCOD)] as the metal source (Scheme 5.10). The use of DMAP as an additive (200 mol%) in THF (rt to 50°C) allowed the regiochemical ortho aromatic C—H replacement (33 vs. 33 ) prevalently. 

Substitution of allylic alcohols with active methylene compounds as a suspension in water was achieved in excellent yields using Pd(PPhj)4 in the presence of a carboxylic add such as l-adamantanecarboxyUc add. Bergbreiter and Liu used a water-soluble, polymer-bound paUadium/phosphine catalyst in water or in mixed aqueous/organic solvents. This polymeric catalyst showed high activity in nucleophilic allylic substitution affording high yields of coupled products, and it could be recycled by solvent or thermal precipitation. 

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