Naim H. Al-Said

Synthesis of bis-diosgenin pyrazine dimers: new cephalostatin analogs.

A convenient synthesis for bis-diosgenin pyrazine dimers, cephalostatin analogues is reported. These symmetrical dimeric steroid-pyrazines were obtained by the classical condensation of alpha-amino ketones, the most efficient method for pyrazine ring construction.

Cyclization of free radicals at the C-7 position of ethyl indole-2-carboxylate derivatives: an entry to a new class of Duocarmycin Analogues.

Aryl free-radicals generated at the C-7 position of ethyl indole-2-carboxylates bearing N-allyl and propargylic groups triggered intramolecular cyclizations to furnish a new class of Duocarmycin analogues, formal ethyl pyrrolo[3,2,1-ij]quinoline-2-carboxylate derivatives, through the less favorable 6-endo-trig cyclization mode.

Synthesis of new symmetrical bis-steroidal pyrazine analogues from diosgenin

New symmetrical bis-steroidal pyrazine dimers that are cephalostatins/ritterazines analogues have been prepared easily from a cheap, readily available natural steroid (diosgenin). These dimers were obtained by classical, condensation of α-amino ketones in order to construct the pyrazine rings. The three dimers differ in the functionalized diosgenin: (25R)-5α,6β-dihydroxy-5α-spirosta-3-one, (25R)-4,5α-epoxy-5β-spirosta-3,6-dione and (25R)-5α-hydroxy-5α-spirosta-3,6-dione respectively.

Naphthaldehyde-derived ligands: synthesis and their Ni(II) ion complexation

Three novel diazacrown ether ligands, namely 17-, 18-, and 20-membered O2N2-donor macrocycles derived from 3,3′-[butane-1,4-diylbis(oxy)]bis(2-naphthalenecarbaldehyde), were prepared and characterized by 1H and 13C NMR spectroscopy and mass spectra. Their host–guest interaction with Ni(II) was studied in DMSO-d6 using 1H NMR spectroscopy. The stoichiometry of the complex in each case in the concentration range examined was determined to be 1:1 using the continuous variation method (Job’s plot). The 17-membered O2N2-donor macrocycle in which the two nitrogen atoms are tethered by three methylene units binds Ni(II) more strongly than the other two macrocycles do.Graphical abstract

Ethyl 2-(3-Methyl-5-oxo-4,5-dihydro-3H-benzo[e][1,4]diazepin-2-ylamino)benzoate

A simple route for synthesis of ethyl 2-(3-methyl-5-oxo-4,5-dihydro-3H-benzo[e][1,4]diazepin-2-ylamino)benzoate is developed. The present work involves condensation of 2-(2-nitrobenzamido)propanoic acid with ethyl anthranillate followed by the H2/Pd/C reduction to give the amino ester which upon heating in DMF in the presence of FeCl3 affords the title compound. The structure of the title compound was established on the basis of 1H-NMR, 13C-NMR and mass spectral data.