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N-Protected amino acids can be easily converted into chiral α-amino aldehydes in a one-pot reaction by activation with CDI followed by reduction with DIBAL-H. This method delivers Boc-, Cbz- and Fmoc-protected amino aldehydes from proteinogenic amino acids in very good isolated yields and complete stereointegrity.

The direct biochemical synthesis of tertiary α-amino acids with a wide range of diversity was recently reported using natural threonine aldolases LTA from Aeromonas jandei and DTA from Pseudomonas sp. Here, we describe the identification of five novel threonine aldolases which accept alanine and serine as amino acid donors. The enzymes were found by sequence database analysis using known aldolases as template. All enzymes were overexpressed in Escherichia coli and purified, and their biochemical properties were characterized. The new enantiocomplementary L- and D-threonine aldolases catalyze the asymmetric synthesis of β-hydroxy α-methyl- and α-hydroxymethyl-α-amino acids with good conversion and perfect enantioselectivity at α-carbon of the products (e.e. >99 %). The structural basis for the broad donor specificity of these threonine aldolases is analyzed based on crystal structure alignments and amino acid sequences comparison.

One of the most common protein-protein interactions (PPI) is the interaction of the α-helix of one protein with the surface of the second one. Terphenylic scaffolds are bioinspired motifs in the inhibition of PPIs and have been identified as suitable α-helix mimetics. One of the challenging aspects of this strategy is the poor solubility of terphenyls under physiological conditions. In the literature pyrrolopyrimidine-, pyrimidine- or pyridazine-based mimetics have been reported to show improved solubility. We present a new convergent strategy for the synthesis of linear pyridine-type teraryls based on a phenylic core unit. A general approach for the synthesis of 3,5-disubstituted pyridine-based boronic acid pinacol esters with amino acid side chains in the 3-position (representing Phe, Leu, Ile, Lys, Asp, Asn) is presented and exploits the functional group tolerance of the Knochel-Grignard reagents. The building blocks have been used in a convergent in situ two-step synthesis of teraryl α-helix mimetics., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Teraryl-based α-helix mimetics have proven to be useful compounds for the inhibition of protein-protein interactions (PPI). We have developed a modular and flexible approach for the synthesis of teraryl-based α-helix mimetics. Central to our strategy is the use of a benzene core unit featuring two leaving groups of differentiated reactivity in the Pd-catalyzed cross-coupling used for terphenyl assembly. With the halogen/diazonium route and the halogen/triflate route, two strategies have successfully been established. The synthesis of core building blocks with aliphatic (Ala, Val, Leu, Ile), aromatic (Phe), polar (Cys, Lys), hydrophilic (Ser, Gln), and acidic (Glu) amino acid side chains are reported., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)