Redox catalysis: Aryl amides, imides, lactams, and dipeptides are obtained through a direct Staudinger ligation mediated by phosphine‐based redox catalysis (see scheme). Mechanistic studies indicate the involvement of a phosphonium carboxylate intermediate that leads to a 1,3‐acyl migration and thus results in CN bond formation.

A chlorophosphite-modified, Staudinger-like acylation of azides involving a highly chemoselective, direct nucleophilic acyl substitution of carboxylic acids is described. The reaction provides the corresponding amides with analytical purity in 32-97% yield after a simple aqueous workup without the need for a pre-activation step. The use of chlorophosphites as dual carboxylic acid-azide activating agents enables the formation of acyl C-N bonds in the presence of a wide range of nucleophilic and electrophilic functional groups, including amines, alcohols, amides, aldehydes, and ketones. The coupling of carboxylic acids and azides for the formation of alkyl amides, sulfonyl amides, lactams, and dipeptides is described.

A titanocene-catalyzed conjugate reduction of alpha,beta-unsaturated carbonyl derivatives has been developed. A series of carbonyl compounds including aldehydes, ketones, esters, and amides proved viable in the reduction process providing an efficient, chemoselective method for the catalytic reduction of unsaturated carbonyl derivatives.

The study presented herein describes a reductive transmetalation approach toward the generation of Grignard and organozinc reagents mediated by a titanocene catalyst. This method enables the metalation of functionalized substrates without loss of functional group compatibility. Allyl zinc reagents and allyl, vinyl, and alkyl Grignard reagents were generated in situ and used in the addition to carbonyl substrates to provide the corresponding carbinols in yields up to 99%. It was discovered that phosphine ligands effectively accelerate the reductive transmetalation event to enable the metalation of C-X bonds at temperatures as low as -40 °C. Performing the reactions in the presence of chiral diamines and amino alcohols led to the enantioselective allylation of aldehydes.

Redox‐Katalyse: Arylamide, Imide, Lactame und Dipeptide werden durch eine direkte Staudinger‐Ligation, die über eine Phosphin‐basierte Redoxkatalyse verläuft, hergestellt (siehe Schema). Mechanistische Studien deuten auf ein Phosphoniumcarboxylat‐Intermediat hin, das zu einer 1,3‐Acylmigration und somit zur Bildung der C‐N‐Bindung führt.