Diastereoselective arylation of enantiopure 3-bromopiperidin-2-one derived from (R)-(−)-2-phenylglycinol with organocuprate reagents

Bicyclic Piperidines via [2 + 2] Photocycloaddition

A synthetic strategy to fused bicyclic piperidines-building blocks for medicinal chemistry-is developed. The key step was an intramolecular [2 + 2]-photocyclization. The photochemical step was performed on a gram scale. Crystallographic analysis of the obtained compounds revealed that they occupy a novel chemical space and can be considered as elongated analogues of 3-substituted piperidines.

Cobalt-Catalyzed Cross-Coupling of α-Bromo Amides with Grignard Reagents

A cobalt-catalyzed cross-coupling between α-bromo amides and Grignard reagents is disclosed. The reaction is general and allows access to a large variety of α-aryl and β,γ-unsaturated amides. Some mechanistic investigations have been undertaken to determine the nature of the intermediate species.

Cobalt-catalyzed cross-coupling of 3- and 4-iodopiperidines with Grignard reagents

A cobalt-catalyzed cross-coupling between 3- and 4-iodopiperidines and Grignard reagents is disclosed. The reaction is an efficient, cheap, chemoselective, and flexible way to functionalize piperidines. This coupling was used as the key step to realize a short synthesis of (±)-preclamol. Some mechanistic investigations were conducted that highlight the formation of radical intermediates.

Chemoselective intermolecular α-arylation of amides

A new approach for the fully chemoselective α-arylation of amides is presented. By means of electrophilic amide activation, aryl groups can be regioselectively introduced α- to amides, even in the presence of esters and alkyl ketones. Mechanistic studies reveal key reaction intermediates and emphasize a remarkably subtle base effect in this transformation.