Psammaceratin A: A Cytotoxic Psammaplysin Dimer Featuring an Unprecedented (2Z,3Z)-2,3-bis(aminomethylene)succinamide Backbone from the Red Sea Sponge Pseudoceratina arabica

Bioassay-guided partition of the extract of the Red Sea sponge Pseudoceratina arabica and HPLC purification of the active fraction gave a psammaplysin dimer, psammaceratin (1), along with psammaplysin A (2). The dimer comprises two units of psammaplysin A (2) connected via the terminal amines with an unprecedented (2Z,3Z)-2,3-bis(aminomethylene)succinamide moiety, and it represents the first dimer to be identified among the psammaplysin family. Data from 1D- and 2D-NMR and HRMS supported the chemical structures of the compounds. Psammaceratin A (1) and psammaplysin A (2) exhibited significant growth inhibition of HCT 116, HeLa, and MBA-MB-231 cells down to 3.1 mM.

Purification of surfactin compounds produced by a Bacillus subtilis strain

Surfactins are lipopeptide-type biosurfactants produced mainly by Bacillus species containing a peptide loop of seven amino acids and a hydrophobic fatty acid chain. These molecules exhibit various biological activities; therefore, their therapeutic and environmental applications are in the focus worldwide. In our work, a multi-step purification and separation process was developed to isolate surfactins from the ferment broth of B. subtilis SZMC 6179J strain. The process incorporates normal phase flash chromatography for pre-purifying the crude extract and two consecutive reverse phase HPLC separations for the isolation of the various surfactin molecules. The determination of the relative amounts of lipopeptides both in the crude extract and in each fraction of every separation step were carried out by HPLC-HESI-MS examinations. The ratio of surfactins in the crude extract was 21.35%, but after the preparative flash chromatographic separation the relative amount of surfactins was observed to be 30.44%. The preparative HPLC purification step resulted 85.39% purity of the surfactins. Nine different surfactin variants were isolated and identified from the fractions of this final semi-preparative HPLC purification, out of which three compounds were completely purified, and three others were detected in relative amounts of more than 95% in some fractions.

Synthesis of a plasmenylethanolamine

A concise synthesis of a plasmenylethanolamine (PlsEtn-[16:0/18:1 n-9]), known as antioxidative phospholipids commonly found in cell membranes, has been achieved from an optically active known diol through eight steps. The key transformations for the synthesis of PlsEtn-[16:0/18:1 n-9] are, (1) regio- and Z-selective vinyl ether formation via alkylation of a lithioalkoxy allyl intermediate with an alkyl iodide, and (2) a one-pot phosphite esterification–oxidation sequence to construct the ethanolamine phosphonate moiety in the presence of the vinyl ether functionality. The piperidine salt of synthetic PlsEtn-[16:0/18:1 n-9] was desalinated through reversed-phase HPLC purification.

Synthesis of New Planar-Chiral Linked [2.2]Paracyclophanes-N-([2.2]-Paracyclophanylcarbamoyl)-4-([2.2]Paracyclophanylcarboxamide, [2.2]Paracyclophanyl-Substituted Triazolthiones and -Substituted Oxadiazoles

The manuscript describes the synthesis of new racemic and chiral linked paracyclophane assigned as N-5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carbamoyl)-5’-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carboxamide. The procedure depends upon the reaction of 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)hydrazide with 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)isocyanate. To prepare the homochiral linked paracyclophane of a compound, the enantioselectivity of 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carbaldehyde (enantiomeric purity 60% ee), was oxidized to the corresponding acid, which on chlorination, gave the corresponding acid chloride of [2.2]paracyclophane. Following up on the same procedure applied for the preparation of racemic-carbamoyl and purified by HPLC purification, we succeeded to obtain the target Sp-Sp-N-5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carbamoyl)-5’-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)carboxamide. Subjecting N-5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)hydrazide to various isothiocyanates, the corresponding paracyclophanyl-acylthiosemicarbazides were obtained. The latter compounds were then cyclized to a new series of 5-(1,4(1,4)-dibenzenacyclohexaphane-12-yl)-2,4-dihydro-3H-1,2,4-triazol-3-thiones. 5-(1,4(1,4)-Dibenzenacyclohexaphane-12-yl)-1,3,4-oxadiazol-2-amines were also synthesized in good yields via internal cyclization of the same paracyclophanyl-acylthiosemicarbazides. NMR, IR, and mass spectra (HRMS) were used to elucidate the structure of the obtained products. The X-ray structure analysis was also used as an unambiguous tool to elucidate the structure of the products.

New Synthetic Route to Tucatinib

A new and improved synthetic route to tucatinib is described that involves three key intermediates. The first of these, 4-([1,2,4]triazolo[1,5-a]pyridin-7-yloxy)-3-methylaniline, was prepared on a 100 g scale in 33% yield over five steps and 99% purity. Next, N 4-(4-([1,2,4]triazolo[1,5-a]pyridin-7-yloxy)-3-methylphenyl)quinazoline-4,6-diamine was isolated in 67% yield over three steps and >99% purity. Then, 4,4-dimethyl-2-(methylthio)-4,5-dihydrooxazole trifluoromethanesulfonate was prepared under mild conditions in 67% yield over two steps. Finally, tucatinib was obtained in 17% yield over nine steps and in >99% purity (HPLC). Purification methods used to isolate the product and the intermediates involved in the route are also reported.