Bifunctional Phase-transfer Catalysts Research Articles

Cascade reactions of glycine Schiff bases and chiral phase transfer catalysts in the synthesis of α-amino acids 3-substituted phthalides or isoindolinones

The tuning of aldol/cyclization cascade reactions of glycine Schiff bases with 2-cyano benzaldehydes provides access to non-natural α-amino acid derivatives substituted alternatively with phthalides or isoindolinones, depending on the strength of the used base. Moreover, a preliminary screening of catalysts and conditions for development of asymmetric versions identified chiral bifunctional phase transfer catalysts as particularly promising, leading to the α-amino esters 3-substituted phthalides in high yields and good diastereo- and enantioselectivity.

Phase-Transfer-Catalyzed Asymmetric Conjugate Cyanation of Alkylidenemalonates with KCN in the Presence of a Brønsted Acid Additive

Highly enantioselective conjugate cyanation of alkylidenemalonates with KCN was achieved under mild phase-transfer conditions with a bifunctional phase-transfer catalyst. The effect of Brønsted acid additives was examined based on the hypothetical catalytic cycle, and the Brønsted acid additive was found to be essential to promote the conjugate cyanation efficiently.

ChemInform Abstract: Designer Chiral Phase‐Transfer Catalysts for Green Sustainable Chemistry

AbstractReview: 36 refs.

Designer chiral phase-transfer catalysts for green sustainable chemistry

A series of chiral quaternary ammonium salts derived from commercially available (R)- or (S)-binaphthol have been designed as new C 2-symmetric chiral phase-transfer catalysts. In order to realize the flexible design of these phase-transfer catalysts, the combinatorial design approach has been developed. Chiral high-performance organocatalysts, thus obtained, have been successfully applied to the highly practical asymmetric synthesis of various amino acid derivatives, including α-alkyl and α,α-dialkyl-α-amino acids in addition to alkaloids. Furthermore, several chiral bifunctional phase-transfer catalysts have been designed and synthesized for effecting base-free phase-transfer reactions under essentially neutral conditions in order to realize green sustainable chemistry.

ChemInform Abstract: Chiral Bifunctional Phase Transfer Catalysts for Asymmetric Fluorination of β‐Keto Esters.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Chiral bifunctional phase transfer catalysts for asymmetric fluorination of β-keto esters

Chiral bifunctional phase transfer catalysts introducing bis(diarylhydroxymethyl) substituents at 3,3'-positions of the chiral binaphthyl core were successfully applied to asymmetric fluorination of cyclic beta-keto esters with high enantioselectivities.

Phase-transfer and metal-complex catalysis with quaternary ammonium chlorometallates

Quaternary ammonium chlorometallates were found to be highly efficient bifunctional metal-complex and phase-transfer catalysts.