Organocatalyzed Michael addition of N‐substituted tetramic acids to nitroalkene acceptors followed by O‐alkylation gave polyfunctionalized tetramic acid (31 examples, 59–94% ee). The ...enantioselectivity of the product was influenced by the N‐substituent of the substrate. Quantum chemical methods provided the mechanistic insights of the studied transformation. The preferred reaction pathway follows the model proposed by Pápai et al. Single crystal structure confirmed the absolute configuration, which was in line with the ECD measured and calculated structure. Additionally, a comparative study of the alkylation of a selected tetramic and tetronic acid with trans‐β‐nitrostyrene is disclosed. Follow‐up amidations demonstrated the applicability of this class of compounds for the incorporation into both dipeptide and depsipeptide sequences.
A three-step synthesis of 1-{(1S,2S,4R)-7,7-dimethyl-1-(pyrrolidin-1-yl)methylbicyclo2.2.1heptan-2-yl}-1H-benzodimidazole, prepared from camphor derived diamine, is disclosed. The absolute ...configuration at the chiral center bearing benzodimidazole moiety was confirmed by NOESY. The structure of a newly synthesized compound was confirmed by 1H- and 13C-NMR, 2D NMR, IR spectroscopy, and high resolution mass-spectrometry.
Organocatalyzed synthesis of tert-butyl 2-amino-3-cyano-5-oxo-4-phenyl-5,7-dihydropyrano2,3-cpyrrole-6(4H)-carboxylate, prepared from Boc-tetramic acid and benzylidenemalononitrile, is disclosed. Two ...bifunctional noncovalent organocatalysts were employed, yielding the product as a racemic mixture in both cases. The structure of the new synthesized compound was confirmed by high resolution mass-spectrometry, 1H- and 13C-NMR, HSQC, and IR spectroscopy.
