Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles

• Pavol Jakubec,
• Dane M. Cockfield,
• Madeleine Helliwell,
• James Raftery and
• Darren J. Dixon

Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64

• ester 6c, provided moderate yields of the desired δ-lactams 1b and 1c as single diastereoisomers in both cases. The diastereoselectivity in the latter case is notable, as the quaternary stereogenic centre is created in the lactamisation step. The relative stereochemical configurations of 1a–c were

Synthesis of enantiomerically enriched (R)-¹³C-labelled 2-aminoisobutyric acid (Aib) by conformational memory in the alkylation of a derivative of L-alanine

• Stephen P. Fletcher,
• Jordi Solà,
• Dean Holt,
• Robert A. Brown and
• Jonathan Clayden

Beilstein J. Org. Chem. 2011, 7, 1304–1309, doi:10.3762/bjoc.7.152

• product was established. Keywords: amino acid; asymmetric synthesis; conformational memory; isotopic label; isotopomer; quaternary stereogenic centre; Introduction In connection with our work on the control of conformation in helical foldamers [1][2][3] built from quaternary α-amino acids [4][5], we