An efficient and concise total synthesis of (+)-lentiginosine (1) starting from an L-tartaric acid-derived nitrone using organometallic addition, indium-catalyzed reduction, and ring-closing metathesis reaction as the key steps is reported. Structural analogues of (+)-1 have been also synthesized, and their inhibitory activity toward 22 commercially available glycosidases has been evaluated.

Over the years, γand δ-amino acids have gathered much interest in drug discovery, especially in the peptidomimetic area. Much work on γ-amino acids has been focused towards the generation of γ-amino butyric acid (GABA) analogues, and the development of asymmetric approaches starting from unsaturated compounds, while few examples have been reported about carbohydrate-derived scaffolds as γ-amino acids. δ-Amino acids became of great importance as they have been selected as building blocks for backbone generation of peptide nucleic acid (PNA) structures. As further applications of δ-amino acids, carbohydrate research produced interesting examples of new δ-amino acids as building blocks for peptidomimetic design, and several reverse turn mimetics have been reported, too. Moreover, many studies have been concentrated on the conformational analysis of oligomeric sequences in analogy with β-peptides. This report is a description of relevant synthetic approaches to new γ-amino acids through the use of sugar chemistry and asymmetric synthesis, and to synthetic strategies for δ-amino acids, covering the area of carbohydrate chemistry, alkenebased chemistry, and asymmetric synthesis. 10γ -and δ -Amino Acids: Synthetic Strategies

No abstract

[reaction: see text]. Iteration of organometallic addition to chiral hydroxylated pyrroline N-oxides through an addition-oxidation-addition synthetic sequence allowed highly stereoselective double alkylation of pyrrolidine at C-2 or at C-2 and C-5 depending on the regioselectivity of the oxidation step. Application of this methodology has been exemplified by the synthesis of the all-substituted pyrrolidine alkaloid (-)-codonopsinine and of proline-type amino acid precursors possessing a quaternary stereogenic center, whose configuration can be controlled.