Palladium‐Catalyzed Carboetherification and Carboamination Reactions of γ‐Hydroxy‐ and γ‐Aminoalkenes for the Synthesis of Tetrahydrofurans and Pyrrolidines

Abstract

The development of Pd-catalyzed carboetherification and carboamination reactions between aryl/alkenyl halides and alkenes bearing pendant heteroatoms is described. These transformations effect the stereoselective construction of useful heterocycles such as tetrahydrofurans, pyrrolidines, imidazolidin-2-ones, isoxazolidines, and piperazines. The scope, limitations, and applications of these reactions are presented, and current stereochemical models are described. The mechanism of product formation, which involves an unusual intramolecular syn-insertion of an alkene into a Pd-Heteroatom bond is also discussed in detail.

Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

“…However, terminal olefins 30 and threo - 9 underwent chlorocyclisation most probably due to the presence of an excess of chloride anions (Table 1, entries 10 and 11). Interestingly, this chlorocyclisation reaction proceeded with high trans -diastereoselectivity, which is in accordance with Wolfe´s TS model [17–18]. In both cases, only 2,3- trans diastereomers 55 and 58 were isolated in good yields.…”

Stereoselective and Regioselective Synthesis of Heterocycles via Copper-Catalyzed Additions of Amine Derivatives and Alcohols to Alkenes

“…14–16 When metals react primarily via two-electron mechanisms (e.g., often for [Pd], [Ni], and [Au]), alkene difunctionalization involves using ligands that prohibit β -hydride elimination, 17 oxidants that oxidize the metal center, 18–20 substrate chelation for conformational restriction 21 or a comparatively higher reductive elimination rate. 22 An alternative strategy involves application of paramagnetic transition metals. Alkene additions catalyzed by these metals result in transient alkyl radicals that can then engage in bond formations with radical acceptors or become oxidized to carbocations that then undergo reaction with nucleophiles (Scheme 1b).…”

Evolution of copper(II) as a new alkene amination promoter and catalyst

“…The simultaneous formation of C–N and C–C bonds across an alkene, heretofore referred to as carboamination, is an attractive method for the synthesis of nitrogen heterocycles [13–15]. Nitrogen heterocycles are common components of bioactive molecules.…”