Synthesis and crystal structures of three Schiff bases derived from 3-formyl-acetyl-acetone and benzyl-, tert-butyl- and (S)-methyl-benzyl-amine.

Treatment of 3-formyl-acetyl-acetone with the amines benzyl-amine, tert-butyl-amine and (S)-methyl-benzyl-amine led to the formation of the corresponding Schiff bases 3-[(benzyl-amino)-methyl-idene]pentane-2,4-dione, C13H15NO2 (1), 3-[(tert-butyl-amino)-methyl-idene]pentan-2,4-dione, C10H17NO2 (2) and 3-{[(S)-benz-yl(meth-yl)amino]-methyl-idene}pentane-2,4-dione, C14H17NO2 (3). The mol-ecules of all three compounds exist as enamine tautomers that contain a nearly planar amino-methyl-ene-pentane-2,4-dione core with a strong intra-molecular N-H⋯O hydrogen bridge. The R group attached to the enamine N atom has no significant influence on the bond lengths and angles of the amino-methyl-ene-pentane-2,4-dione core. The supra-molecular structures in 1-3 are mainly based on weak C-H⋯O hydrogen bonds.

Synthesis and crystal structures of three Schiff bases derived from 3-formyl-acetyl-acetone and o-, m- and p-amino-benzoic acid.

Treatment of 3-formyl-acetyl-acetone with the isomeric o-, m- and p-amino-benzoic acids led to the formation of the corresponding Schiff bases, namely, 3-[(2-carb-oxy-phenyl-amino)-methyl-idene]pentane-2,4-dione, 1, 3-[(3-carb-oxy-phenyl-amino)-methyl-idene]pentane-2,4-dione, 2, and 3-[(4-carb-oxy-phenyl-amino)-methyl-idene]pentane-2,4-dione, 3, all C13H13NO4, that contain a planar amino-methyl-ene-pentane-2,4-dione core with a strong intra-molecular N-H⋯O hydrogen bridge. The carb-oxy-phenyl groups attached to the nitro-gen atom are almost coplanar to the central mol-ecular fragment. Depending on the position of the carboxyl unit, different supra-molecular structures with hydrogen-bonding networks are formed in the three title structures.

Racemization-free synthesis of Nα-2-thiophenoyl-phenylalanine-2-morpholinoanilide enantiomers and their antimycobacterial activity.

Nα-2-thiophenoyl-D-phenylalanine-2-morpholinoanilide (MMV688845, IUPAC: N-(1-((2-morpholinophenyl)amino)-1-oxo-3-phenylpropan-2-yl)thiophene-2-carboxamide) from the Pathogen Box® library (Medicines for Malaria Ventures, MMV) is a promising lead compound for antimycobacterial drug development. Two straightforward synthetic routes to the title compound starting from phenylalanine or its Boc-protected derivative are reported. Employing Boc-phenylalanine as starting material and the T3P® and PyBOP® amide coupling reagents enables racemization-free synthesis, avoiding the need for subsequent separation of the enantiomers. The crystal structure of the racemic counterpart gives insight into the molecular structure and hydrogen bonding interactions in the solid state. The R-enantiomer of the title compound (derived from D-phenylalanine) exhibits activity against non-pathogenic and pathogenic mycobacterial strains, whereas the S-enantiomer is inactive. Neither of the enantiomers and the racemate of the title compound shows cytotoxicity against various mammalian cells.

Syntheses and crystal structures of three [M(acac)2(TMEDA)] complexes (M = Mn, Fe and Zn).

The complexes bis-(acetyl-acetonato-κ2 O,O')(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')manganese(II), [Mn(C5H7O2)2(C6H16N2)], bis-(acetyl-acetonato-κ2 O,O')(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')iron(II), [Fe(C5H7O2)2(C6H16N2)], and bis-(acetyl-acetonato-κ2 O,O')(N,N,N',N'-tetra-methyl-ethylenedi-amine-κ2 N,N')zinc(II), [Zn(C5H7O2)2(C6H16N2)], were synthesized from the reaction of the corresponding metal acetyl-acetonates [M(acac)2(H2O)2] with N,N,N',N'-tetra-methyl-ethylenedi-amine (TMEDA) in toluene. Each of the complexes displays a central metal atom which is nearly octa-hedrally surrounded by two chelating acac and one chelating TMEDA ligand, resulting in an N2O4 coordination set. Despite the chemical similarity of the complex units, the packing patterns for compounds 1-3 are different and thus the crystal structures are not isotypic.