Amines, metal catalyzed conjugate addition

The l ,J -DBFOX/Ph-transition metal aqua complex catalysts should be suitable for the further applications to conjugate addition reactions of carbon nucleophiles [90-92]. What we challenged is the double activation method as a new methodology of catalyzed asymmetric reactions. Therein donor and acceptor molecules are both activated by achiral Lewis amines and chiral Lewis acids, respectively the chiral Lewis acid catalysts used in this reaction are J ,J -DBFOX/Ph-transition metal aqua complexes. 

The Michael reaction is the conjugate addition of a soft enolate, commonly derived from a P-dicarbonyl compound 24, to an acceptor-activated alkene such as enone 41a, resulting in a 1,5-dioxo constituted product 42 (Scheme 8.14) [52]. Traditionally, these reactions are catalyzed by Bronsted bases such as tertiary amines and alkali metal alkoxides and hydroxides. However, the strongly basic conditions are often a limiting factor since they can cause undesirable side- and subsequent reactions, such as aldol cyclizations and retro-Claisen-type decompositions. To address this issue, acid- [53] and metal-catalyzed [54] Michael reactions have been developed in order to carry out the reactions under milder conditions. 

Mechanistically, two scenarios have been advanced. The first involves coordination of the nitrile to the Ru center which is followed by nucleophilic attack at the nitrile, while the second entails a sequence of events starting with oxidative addition of water, an alcohol or an amine to the metal center, followed by insertion of the nitrile into the Ru-OH bond. A recent report describes the conjugate addition of alcohols to acrylonitrile compounds catalyzed by a mthenium-acetamido complex [Ru(PCy3)2(CO)(CH3CONH)-(i-PrOH)H] (7) (Scheme 10.13) [17]. The mechanistic investigation of this reaction supports the proposal that the N-coordination of acrylo-... 

Balme has reported a one-pot threecomponent alkene carboamination between propargylic amines, alkylidene malonates, and aryl halides [43]. For example, treatment of N-methyl propargylamine (2 equiv), dimethyl benzylidene malonate (2 equiv) and 1,4-diiodobenzene (1 equiv) with n-BuLi and a palladium catalyst provided 43 as a single diastereomer (Eq. (1.20)) [43a]. The formation of the C—N bond in this process does not appear to be metal catalyzed. Instead, initial conjugate addition of the nitrogen nucleophile to the activated alkene affords a malonate anion, which undergoes carbopalladation followed by reductive elimination to afford the pyrrolidine product. 

Reductive nitrosylation, on the other hand, can refer to the addition of NO to a metal center Mox with formal reduction of the metal center to yield Mred(NO +), but in the context of ligand reactions reductive nitrosylation refers to the net reactions of NO with metal-bound NO and the ensuing events. Reductive nitrosation of coordinated amines to form nitrosamines occurs through the conjugate base of the amine, and this process has been reported for reactions of NO with [Ni(tacn)2]3 +, 198 with methyl-amine coordinated to a macrocyclic Ni(III) complex,199 with triglycyl complexes of Fe(III), Ni(III), and Cu(III),200 and with Cu(II) macrocyclic complexes.201 Reductive nitrosation of [Ru(NH3)6]3+ produces [Ru(NH3)5N2]2 + with base-catalyzed kinetics the coordinated N2 is produced by hydrolysis after the nitrosation step.170... 

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