Stereoselective synthesis of α,α′-bridged bis(α-alanine) derivatives

Synthesis and applications of symmetric amino acid derivatives

Symmetric α-amino acid derivatives can be used for the synthesis of intermolecularly linked peptides such as dimer-type peptides, and modified peptides in which two amino acids are intramolecularly linked. They are also synthetic intermediates for the total synthesis of natural products and functional molecules. These symmetric amino acid derivatives must be prepared based on organic synthesis. It is necessary to develop an optimal synthetic strategy for constructing the target symmetric amino acid derivative. In this review, we will introduce strategies for synthesizing symmetric amino acid derivatives. Additionally, selected applications of these amino acids in the life sciences will be described.

The Schöllkopf chiron and transition metal mediated reactions, a powerful combination for stereoselective construction of cyclic α-quaternary-α-amino acid derivatives

The focus has been on the development of methodology for stereoselective preparation of spiroannulated intermediates of the Schöllkopf chiron and further transformations to cyclic alpha-amino acids. The spiroannulations are effected by Ru(II)-catalysed ring-closing metathesis reactions, by Ru(II)- and Pd(0)-catalysed cycloisomerisations, by Rh(II)-carbenoid cyclisation reactions and by intramolecular aldol condensations. Hydrolytic reactions of the spirane intermediates have provided several groups of highly novel and functionalised five-, six- and seven-membered cyclic alpha-quaternary-alpha-amino acid derivatives as well as alicyclic derivatives. The novel cyclic amino acid derivatives can be regarded as cyclic constrained analogues of corresponding common amino acids, or in some cases as intermediates for further preparation of such amino acids. Some emphasis has been on the preparation of cyclic serine analogues. Major efforts have been on the preparation of cyclic alpha-quaternary bis(alpha-amino acid) derivatives as conformationally constrained dicarba-analogues of cystine.

Synthesis of bis-armed amino acid derivatives via the alkylation of ethyl isocyanoacetate and the Suzuki–Miyaura cross-coupling reaction

Two synthetic routes to bis-armed-alpha-amino acid derivatives are described. The first route involves alkylation of dibromo derivatives with ethyl isocyanoacetate under phase-transfer catalysis (PTC) conditions. The second route uses a palladium-mediated Suzuki-Miyaura cross-coupling reaction between a DL-4-boronophenylalanine derivative and aromatic diiodo (or dibromo) compounds.

Development of an isotope-coded activity-based probe for the quantitative profiling of cysteine proteases

Quantification studies of complex protein mixtures have been restricted mainly to whole cell extracts. Here we describe the synthesis of two sets of isotope-coded activity-based probes that allow quantitative functional proteomics experiments on the cathepsins.