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The development of two novel bifunctional amine-thiourea organocatalysts both of which bear central and axial chiral elements to promote the enantioselective Michael reaction between 1,3-dicarbonyl compounds and nitro olefins is reported. The bifunctional amine-thiourea organocatalysts might have potential use for the design of novel chiral organocatalysts.

(+)-Alopecuridine, (+)-sieboldine A, and (-)-lycojapodine A, three structurally unique and related lycopodium alkaloids, have been synthesized in enantiomeric forms through an efficient strategy. The main synthetic approach for (+)-alopecuridine features a semipinacol rearrangement of hydroxyl epoxide to construct the spiro 6,9-azacarbocycIes with an all-carbon quaternary center and a late-stage SmI2-mediated intramolecular coupling to form the S-membered ring. Subsequently, the biomimetic synthesis of (+)-sieboldine A and (-)-lycojapodine A was accomplished successfully through two different bioinspired oxidations after a wide search for the oxidation methods. As a result, (+)-sieboldine A was derived from (+)-alopecuridine through an N-oxidation/nitrone formation process and (-)-lycojapodine A through an interesting cyclic hemiketal formation/oxidative diol cleavage pathway. These results confirmed the biogenetic relationship among the three alkaloids. [ABSTRACT FROM AUTHOR]

Examines the current efforts being made to design and synthesize enantioselectively peptidomimetic building blocks on a large scale. Most common families used in the construction of nonproteinogenic amino acid building blocks; Problems experienced in the building of these blocks.

Describes a synthetic route to orthogonally protected stereoisomeric derivatives of the amino acid lanthionine using the protected serine beta-lactone, N-CBz-(S)-3-amino-2-oxetanone. Pathways involved in the ring opening of the beta-lactone; Cesium as counterion; Suppression of thioester formation; Schematic explanation for the regioselectivity of the reactions.