Utilization of Chromone-3-Carboxylic Acids as Acceptors in the Michael-Type Decarboxylative Addition

Doubly Decarboxylative Synthesis of 4-(Pyridylmethyl)chroman-2-ones and 2-(Pyridylmethyl)chroman-4-ones under Mild Reaction Conditions

The doubly decarboxylative Michael-type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has been confirmed by mechanistic studies. Moreover, attempts to develop an enantioselective variant of the cascade are also described.

Asymmetric construction of six vicinal stereogenic centers on hexahydroxanthones via organocatalytic one-pot reactions

Inspired by the chemistry and biology of hexahydroxanthones, herein we report an organocatalytic Michael-Michael-Aldol-decarboxylation reaction that provides efficient access to biologically interesting fully substituted hexahydroxanthones bearing six contiguous stereogenic centers from readily accessible materials in acceptable yields (up to 63%) and excellent stereoselectivities (up to 10 : 1 dr and >99% ee). In other words, the reaction efficiently produces three chemical bonds and up to six vicinal stereogenic centers in a one-pot operation. In particular, to our knowledge, this is an asymmetric organocatalytic strategy enabling the first construction of six vicinal stereogenic centers on non-spirocyclic hexahydroxanthone frameworks.

Pyridylacetic acids and related systems as alkylheteroarene surrogates in asymmetric decarboxylative Michael addition

In this manuscript, a novel method for the preparation of enantiomerically enriched pyridine derivatives has been described. It is based on the utilization of readily available 2-pyridylacetic acids as valuable synthons for the introduction of a pyridine ring in an asymmetric fashion. They have been used as pronucleophiles in asymmetric decarboxylative Michael addition to α,β-unsaturated aldehydes. The synthesis based on iminium activation using a chiral aminocatalyst that controlled the stereochemical outcome of the transformation has been successfully accomplished.

Catalytic enantioselective decarboxylative nucleophilic addition reactions using chiral organocatalysts

Catalytic decarboxylative reactions are attractive as biomimetic and environmentally friendly reaction processes. This review summarizes the recent results of organocatalytic enantioselective decarboxylative reactions of malonic acid half oxy- or thioesters, β-ketoacids, and related compounds from October 2013 to December 2019.

Enantioselective Synthesis of Chromanones Bearing an α,α-Disubstituted α-Amino Acid Moiety via Decarboxylative Michael Reaction

In this manuscript, a novel, decarboxylative Michael reaction between α-substituted azlactones and chromone-3-carboxylic acids is described. The reaction proceeds in a sequence Michael addition followed by decarboxylative deprotonation, and it results in the formation of chromanones bearing an azlactone structural unit. The possibility of transforming an azlactone moiety into a protected α,α-disubstituted α-amino acid derivative is also demonstrated.