Synthesis and V-ATPase inhibition of simplified lobatamide analogues

[structure: see text] Simplified analogues of the lobatamides have been synthesized and evaluated for inhibition of bovine V-ATPase. The salicylate phenol, enamide NH, and the ortho-substitution of the salicylate ester have been shown to be important for V-ATPase inhibitory activity.     

Synthesis of linear tuftsin analogues modified at the ε-amino group of lysine

In this Letter, eight tuftsin analogues, seven of which are novel, are presented. All the linear tuftsin analogues contain an isopeptide bond. Modification of the tuftsin chain was based on the introduction of simple amino acids such as valine, glycine, alanine and β-alanine into the peptide chain at the ε-amino group of lysine. The peptides were synthesized by a solid-phase method using the standard Fmoc procedure. Simultaneous deprotection of the peptide side chain and liberation from the resin was achieved using TFA, and the free novel tuftsin analogues were purified and characterized.     

Synthetic and modified isoflavonoids III. Synthesis of benzodioxane analogues of pseudobaptigenin

Benzodioxane analogues of pseudobaptigenin with alkyl fragments in positions 2 and 6 of the chromone ring have been synthesized from -(1,4-benzodioxan-6-yl)-2-hydroxy-6-alkylacetophenones.Taras Shevchenko Kiev University, KIEN. Karakalpak Division, Uzbekistan Academy of Sciences, Nukus. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 808–814, November–December, 1993.     

Synthetic and modified isoflavonoids. XIII. Synthesis of analogues of fujikinin

Analogues of a natural isoflavone glycoside — fujikinin — have been synthesized. Their structures have been confirmed by their PMR spectra.     

Synthetic and modified isoflavonoids IV. Synthesis of benzodioxepane analogues of pseudobaptigenin

Benzodioxepane analogues of pseudobaptigenin have been synthesized and their structures have been established by chemical transformations, elementary analysis, and PMR spectroscopsy.     

Synthetic and modified isoflavonoids. XIII. Synthesis of analogues of fujikinin

Analogues of a natural isoflavone glycoside — fujikinin — have been synthesized. Their structures have been confirmed by their PMR spectra.Taras Shevenko Kiev University: KIEN, Karakalpak Division, Academy of Sciences of the Republic of Uzbekistan, Nukus. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 347–351, May–June, 1994.     

Synthetic and modified isoflavonoids III. Synthesis of benzodioxane analogues of pseudobaptigenin

Benzodioxepane analogues of pseudobaptigenin have been synthesized and their structures have been established by chemical transformations, elementary analysis, and PMR spectroscopsy. Taras Shevchenko Kiev University KIEN. Karakalpak Branch, Uzbekistan Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 814–820, November–December, 1993.     

Synthetic and modified isoflavonoids IV. Synthesis of benzodioxepane analogues of pseudobaptigenin

Benzodioxepane analogues of pseudobaptigenin have been synthesized and their structures have been established by chemical transformations, elementary analysis, and PMR spectroscopsy.Taras Shevchenko Kiev University KIEN. Karakalpak Branch, Uzbekistan Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 814–820, November–December, 1993.     

Synthesis of N-1 and ribose modified inosine analogues on solid support

Herein, we report the synthesis and the use of new N-1-dinitrophenyl-inosine based solid supports, in which the C-2 of the purine base is strongly activated toward the attack of N-nucleophiles. The synthesized supports, binding the nucleoside by a 5′-O-monomethoxytrityl function, have been used to accomplish the synthesis of a small library of N-1 alkylated inosine and AICAR derivatives. In addition, cleavage of the 2′-3′ ribose bond of N-1 alkylated inosine derivatives anchored to the supports allowed to prepare a new set of N-1 alkylated-2′,3′-secoinosine derivatives in high yields.     

Synthesis and HIV-1 integrase inhibition of novel bis- or tetra-coumarin analogues

Present studies were undertaken on the preparation of synthetic analogues of bis- or tetra-coumarins and their activity against HIV-1 integrase (HIV-1 IN). Among these coumarin analogues, compounds 14, 16 and 18 were found to be potent molecules against HIV-1 IN at IC50 values of 0.96, 0.58, and 0.49 microM, respectively. The results provided a tool for guiding the further design of more potent antiviral agents and for predicting the affinity of related compounds.     

Synthesis and bioluminescence of electronically modified and rotationally restricted colour-shifting infraluciferin analogues

Synthetic nIR emitting luciferins can enable clearer bioluminescent imaging in blood and tissue. A limiting factor for all synthetic luciferins is their reduced light output with respect to D-luciferin. In this work we explore a design feature of whether rigidification of an exceptionally red synthetic luciferin, infraluciferin, can increase light output through a reduction in the degrees of freedom of the molecule. A rigid analogue pyridobenzimidazole infraluciferin was prepared and its bioluminescence properties compared with its non-rigid counterpart benzimidazole infraluciferin, luciferin, infraluciferin and benzimidazole luciferin. The results support the concept that synthetic rigidification of π-extended luciferins can increase bioluminescence activity while maintaining nIR bioluminescence.     

Synthesis of novel discodermolide analogues with modified hydrogen-bonding donor/acceptor sites

A series of novel structural analogues of the potent microtubule-stabilizing anticancer agent discodermolide were synthesised, with modifications in the C16-C20 region to create new oxygenated H-bonding donor/acceptor sites for tubulin binding. By starting from an advanced C9-C24 intermediate, fully synthetic discodermolide analogues, incorporating either an additional hydroxyl group 3, an oxetane 4 or a cyclic carbonate 5, were obtained in 10 or 11 steps by using a versatile aldol construction of the C6-C7 bond.     

Synthesis and glycosidase inhibition of C-7 modified casuarine derivatives

A series of C-7 modified analogues of casuarine have been synthesized from sugar-derived nitrone and assayed against various glycosidases. Introduction of C-7 aminomethyl or amide group led to sharp decrease of the inhibitory activities.     

Synthetic and modified isoflavonoids V. Synthesis of 2-trifluoromethyl-substituted analogues of pseudobaptigenin

New two-trifluoromethylchromones with 1,3-benzodioxole and 1,4-benzodioxane nuclei in position 3 have been synthesized.Taras Shevchenko Kiev University KIEN. Karakalpak Division, Uzbekistan Academy of Sciences, Nukus. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 820–822, November–December, 1993.     

Synthetic and modified isoflavonoids V. Synthesis of 2-trifluoromethyl-substituted analogues of pseudobaptigenin

New two-trifluoromethylchromones with 1,3-benzodioxole and 1,4-benzodioxane nuclei in position 3 have been synthesized. Taras Shevchenko Kiev University KIEN. Karakalpak Division, Uzbekistan Academy of Sciences, Nukus. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 820–822, November–December, 1993.     

Polyhydroxylated homoazepanes and 1-deoxy-homonojirimycin analogues: Synthesis and glycosidase inhibition study

The Johnson-Claisen rearrangement of D-gluco and L-ido-derived allylic orthoesters afforded gamma,delta-unsaturated ester that on ester reduction, epoxidation, regioselective oxirane opening by sodium azide and hydrogenation led to sugar amino alcohols--immediate precursors for 1-deoxy-homonojirimycin 3a,b, and polyhydroxylated homoazepanes 4a,b. Our synthetic approach and glycosidase inhibitory activity is reported.     

A modified polymethylsilane as the precursor for ceramic matrix composites

A novel SiC precursor, A-PMS, was synthesized through a reaction of polymethylsilane (PMS) with SbCl₃, where the Si-H in PMS reacts with Sb-Cl to form Si-Sb bond with HCl evaporated. A-PMS was used as a precursor to prepare C_f/SiC ceramic matrix composites (CMCs) via polymer infiltration and pyrolysis (PIP) process. It is evident that SbCl₃ plays a very important role in promoting chain crosslinking, transforming of the Si-Si into Si-C bonds and stabilizing PMS from very high oxidation trend of the active Si-H bonds. A-PMS keeps liquid at room temperature that is suitable for the infiltration in the absence of any solvent. A-PMS can be cured into a fully crosslinked structure at 320 °C that leads to a very high ceramic yield up to 91% and an Si/C ratio near 1.12 after pyrolysis. The resulted CMCs samples reached a density of 1.76 g cm⁻³ and a flexural strength of 381 MPa after only four infiltration-pyrolysis cycles.     

Synthesis of analogues of the iridolactones

Two stereoisomeric lactones of 2(2′-hydroxy-4′-methylcyclohex-1′-yl)propionic acid, analogues of the iridolactones, have been synthesized from -citronellal.     

Solvent-free thermocyclization of the unactivated linear gramicidin S precursor and analogues

A convenient thermocyclization of the linear gramicidin S precursor and its analogues is demonstrated. With the preorganized β-sheet conformation, the unactivated linear precursors can cyclize into the corresponding head-to-tail cyclic products in high yield after being heated under solvent-free conditions.