α-Carboxylate Phosphabetains in Alkylation and Complexation Reactions

Selective complexation of α-amino acids and simple peptides via their carboxylate groups.

The complexation of anions of selected α-amino acids (alanine, valine, proline, tyrosine) and small peptides (L-alanyl-L-alanine, L-alanyl-L-alanyl-L-alanine, and L-alanyl-L-alanyl-L-alanyl-L-alanine) by the dinuclear nickel(II) complex [LNi2(μ-Cl)]+ (1), where (L)2− represents a 24-membered binucleating hexamine-dithiophenolato ligand, has been investigated. The following complexes were prepar...

Enantioselective Decarboxylative Alkylation Reactions: Catalyst

α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursors: enol carbonates, enol silanes, and racemic β-k...

Reactions of Oxime Dianions: Stereospecificity in Alkylation

n carbon.L However, no information on the stereochemistry of the alkylated products was ever reported. We now wish to report total stereospecificity in the formation and alkylation of the a-carbon, oxygen-dianions of aliphatic ketoximes. Treatment of acetoxime 1 with two equivalents of n-BuLi in THF at O°C for 15 minutes resulted in the formation of exclusively the x dianion 2, which upon deute...

Unusual Allylpalladium Carboxylate Complexes: Identification of the Resting State of Catalytic Enantioselective Decarboxylative Ketone Allylic Alkylation Reactions**

Palladium poprocks: Hold on to your CO2! Enantioselective Pd-catalyzed decarboxylative alkylation of ketone enolates proceeds via η1-σ-allyl Pd-carboxylate complexes by slow loss of CO2.

Unusual allylpalladium carboxylate complexes: identification of the resting state of catalytic enantioselective decarboxylative allylic alkylation reactions of ketones.