Synthesis and metal complexation of chiral 3-mono-or 3, 3-bis-allyl-2-hydroxypyrrolopyrazine-1, 4-diones

A novel synthesis of chiral cyclic hydroxamic acids (4, 6, 8 and 10) related to cyclodipeptides is described. The crucial reduction of the nitro group of the N-nitroacetyl derivatives of (S)-α-amino acid esters is brought about by zinc-aq. ammonium chloride. The FeIII and CuII complexes of one such cyclic hydroxamic acid 10a have been prepared and their DNAse activity investigated

Synthesis of novel cyclic hydroxamic acids

The nitroacetyl (S)-proline esters (1,3,5) are reduced by zinc-NH4Cl to the hydroxylamine stage and cyclized to provide the novel chiral bicyclic hydroxamic acids (2,4,6). Michael addition of allyl acrylate on nitroacetic acid derivatives followed by Pd(0) catalyzed intramolecular allyl transfer and subsequent reduction of the nitro group yielded a novel class of cyclic hydroxamic acids related to pyroglutamic acid

Nitroacetyl group as a peptide synthon: synthesis of dipeptides with an α,α-bisallylglycine residue at the N-terminus

N-Nitroacetyl derivatives of L-proline, L-valine, and L-phenylalanine esters were prepared in two steps under mild conditions (Scheme 2). Regiospecific mono- and bis-allylation of these nitroacetyl derivatives were accomplished in presence of a Pd(0) catalyst. The bis-allyl derivatives 7-9 were obtained in 40-75% yield. The tertiary NO<SUB>2</SUB> group in these compounds could be transformed into an acetylamino group by Zn/AcOH/Ac<SUB>2</SUB>O. The final products 11-13 are dipeptides in which the N-terminal glycine residue bears two α-allyl substituents

Utilization of industrial waste materials, 6. Utilization of derivatives of the bicyclic proline analog (all-R)-octahydrocyclopenta[b]pyrrol-2-carboxylic acid in the stereoselective synthesis

Utilization of the industrial waste material benzyl (all-R)-cyclopenta[b]pyrrol-2-carboxylate 1a or its derivatives 1b, 1c as chiral auxiliaries is described. Allylation of nitrothioacetamides, proceeding by initial S-allylation followed by a facile thio Claisen rearrangement, is accomplished with a diastereomeric ratio (dr) up to 85:15 using 1a, b as auxiliaries in stoichiometric amounts. Another aspect of this report is the diastereoselective synthesis of optically active amines, starting from aldehydes, with optical purities (op) up to 99%, Again a derivative of 1a was used as source of chirality