Base Effect on the Palladium Catalyzed α-Arylation ofN-Benzyl-2-Piperidinones

Abstract

A very simple method for obtaining a-arylated N-benzyl-2-piperidinones in high yields is described. The use of s-BuLi as the base and Pd(dba) 2 as the catalyst are the key factors.

Metal‐Catalyzed α‐Arylation of Carbonyl and Related Molecules: Novel Trends in CC Bond Formation by CH Bond Functionalization

“…Cossy and co-workers developed a process based on the use of a palladium catalyst derived from biphenyl monophosphine ligand 7 to extend the substrate scope of the aarylation reactions to include Reformatsky reagents formed from cyclic amides. [89] It was postulated that amines such as hexamethyldisilazane (HMDS) present in the reaction mixture could chelate to the zinc enolate dimer to form I (Scheme 26). Furthermore, the zinc enolate may be protonated by the amine to generate the amide and species II.…”

Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

“…15,16 A variety of reactions of ketone, 17-22 ester, 23-28 amide, 29-32 and aldehyde 33,34 enolates have now been reported, but the use of strongly basic and nucleophlic alkali metal enolates limits the scope of these reactions. In addition, the arylated product, which is more acidic than the reactant, quenches the starting enolate, and products from undesired diarylation have formed.…”

“…The palladium-catalyzed α-arylation of carbonyl compounds has been introduced as a mild, catalytic method to form the C–C bond between an aryl ring and the α-position of a carbonyl compound. , A variety of reactions of ketone, − ester, − amide, − and aldehyde , enolates have now been reported, but the use of strongly basic and nucleophlic alkali metal enolates limits the scope of these reactions. In addition, the arylated product, which is more acidic than the reactant, quenches the starting enolate, and products from undesired diarylation are formed.…”

Palladium-catalyzed α-arylation of N-protected 2-piperidinones

“…Whatever the aryl bromides employed, except the 2,6-dimethyl bromobenzene for which no trace of the coupling product was detected, the palladium-catalyzed coupling products were isolated in excellent yields (from 70 to 99%). 12 The results are reported in Table 6.…”