Peptides and peptidoaldehydes as substrates for the Pictet-Spengler reaction.

The Pictet-Spengler (PS) reaction was performed with various types of substrates: H-Trp-OMe and dipeptides with N-terminal Trp as arylethylamine components and Z-protected amino aldehydes and peptidoaldehydes as carbonyl components. We found that the C-terminal part of Trp derivatives did not have any influence on the stereoselectivity of the reaction and the results are the same for simple esters of Trp and dipeptides. On the contrary, the selectivity of the PS reaction with peptidoaldehydes with L configuration of the C-terminus residue is totally different from that obtained with simple L-amino aldehydes.

Microwave-enhanced solid-phase synthesis of N,N'-linked aliphatic oligoureas and related hybrids.

A practical and efficient microwave-assisted solid-phase method for the synthesis of N,N'-linked oligoureas and related amide/urea hybrid oligomers, featuring the use of succinimidyl (2-azido-2-substituted ethyl) carbamate monomers, is reported. The rate enhancement of urea formation under microwave irradiation combined with the mild conditions of the phosphine-based azide reduction makes this approach very effective for routine synthesis of oligoureas and possibly for library production.

Pictet-Spengler reactions for the synthesis of pharmaceutically relevant heterocycles.

The synthesis of biologically active heterocyclic scaffolds is one of the significant challenges of modern synthetic chemistry. The Pictet-Spengler (PS) reaction, known for approximately a century, remains a particularly popular cyclization method. This review describes recent applications of the PS reaction in the total synthesis of alkaloids and biologically active analogs of tetrahydroisoquinoline and tetrahydro-β-carboline.

New tetracyclic tetrahydro-beta-carbolines as tryptophan-derived peptidomimetics.

The Pictet-Spengler reaction is known as a useful tool for the synthesis of constrained analogs of tryptophan. Herein, we present the further cyclization of 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid methyl esters with 1-(1'-aminoalkyl) side chain. These transformations lead to heterocyclic structures which can find useful applications in medicinal chemistry as peptide mimetics.

pH and temperature-sensitive N-isopropylacrylamide ampholytic networks incorporating L-lysine.

Ampholytic polymer gels based on N-isopropylacrylamide (NIPA) and natural amino acid L-lysine were prepared by free radical polymerization in aqueous solutions. To make amino acids attachable to the polymer chain, the acrylic group was added to the epsilon-amino group of lysine to obtain N-epsilon-acrylic-lysine (Z). Finally, a new temperature- and pH-sensitive (NIPA-Z) hydrogel was obtained.