Molecular structure of carbene analogs

The geometrical parameters of all carbene analogs, halocarbenes, and the corresponding tetrahalides obtained from experimental data and high-level quantum-chemical calculations were collected. Trends in their variations are interpreted using the VSEPR model and by consideration of the HOMOs and LUMOs.     

Sequence and modified group analysis on C-terminal modified analogs of endomorphin-2 using electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometer

In this paper, a series of C-terminal modified analogs of endomorphin-2 is investigated using ESI-FT-ICR-MS. Some b, y″, a, and internal ions are found in the CID spectra and slight mass differ- ences between the calculated and observed results are obtained. Moreover, if the C-terminal modified group is t-butyloxy, it can lose butene through McLafferty rearrangement. FT-ICR MS shows its power in peptide sequencing successfully helping us obtain the structure of peptide analogs.     

Synthesis of Quinoline Analogs: Search for Antimalarial Agents

Summary. Novel synthesis routes for the promising antimalarial agents 4(3-hydroxypyrrolidin-1-yl) and 4(3-hydroxypiperidine-1-yl)-2,8-bis(trifluoromethyl)quinoline have been developed.     

An expeditious entry to rare tetrahydroimidazo[1,5-c]pyrrolo[1,2-a]pyrimidin-7(8H)-ones: A single-step gateway synthesis of glochidine congeners

A single-step gateway synthesis of glochidine and its congeners that possess the rare uncommon tetrahydroimidazo[1,5-c]pyrrolo[1,2-a]pyrimidine core was developed employing histamine and readily available γ-ketoesters. Key features of the developed reaction involve tandem three C–N bonds formation and concomitant annulation of two rings in one pot to access this unique and complex tricyclic structure. Exploration of the unknown bioactivity of these compounds revealed that they elicit antiproliferative activity comparable to the anticancer drug imatinib against 6 cancer cell lines.     

High‐performance liquid chromatographic and subcritical fluid chromatographic separation of α‐arylated ß‐carboline,N‐alkylated tetrahydroisoquinolines and their bioisosteres on polysaccharide‐based chiral stationary phases

New, pharmacologically interesting chiral amino compounds, namely, stereoisomers of α‐hydroxynaphthyl‐ß‐carboline, benz[d]azepine and benz[c]azepine analogs as well as N‐α‐hydroxynaphthylbenzyl‐substituted isoquinolines were enantioseparated by high‐performance liquid chromatographic and subcritical fluid chromatographic methods on polysaccharide‐based chiral stationary phases. Separation of the stereoisomers was optimized in both subcritical fluid chromatography and normal phase liquid chromatographic modes by investigating the effects of the composition of the bulk solvent, temperature, and the structures of the analytes and selectors. Both normal phase liquid chromatography and subcritical fluid chromatography exhibited satisfactory performance, albeit with somewhat different effectiveness in the separation of the stereoisomers studied. The optimized methods offer the possibility to apply preparative‐scale separations thereby enabling further pharmacological investigations of the enantiomers.     

Synthesis of “Reversed” Pyrazole‐C‐nucleoside Precursors from Push‐pull Activated Monosaccharide Derivatives

3‐O‐Benzyl‐6‐deoxy‐1,2‐O‐isopropylidene‐α‐d‐xylo‐hept‐5‐ulofuranurononitrile (1) was reacted with N,N‐dimethylformamide dimethylacetal in tetrahydrofuran to furnish the (E)‐3‐O‐benzyl‐6‐deoxy‐6‐dimethylaminomethylene‐1,2‐O‐isopropylidene‐α‐d‐xylo‐hept‐5‐ulofuranurononitrile (2) as a major product. Furthermore, treatment of compound 1 with carbon disulphide and methyl iodide under basic conditions afforded 3‐O‐benzyl‐6‐deoxy‐1,2‐O‐isopropylidene‐6‐[bis(methylsulfanyl)methylene]‐α‐d‐xylo‐hept‐5‐ulofuranurononitrile (6). Reaction of 2 and 6 with hydrazines yielded the “reversed” pyrazole‐C‐nucleoside analogs 4, 5a, 5b, 7, 8, and 9, respectively.     

Rational design of first generation inhibitors for trehalose 6-phosphate phosphatases

In this study, trehalose 6-phosphate phosphatase (T6PP) was targeted for inhibitor development. T6PP catalyzes the hydrolysis of trehalose-6-phosphate to form trehalose and inorganic phosphate, a reaction essential to important fungal, bacterial, and nematodal pathogens. At the current time, there are no specific inhibitors of T6PP available to serve as tools for interrogating its structure and function nor as leads for pharmaceutical applications. Herein, we describe the synthesis of non-hydrolysable mimics of trehalose-6-phosphate, which incorporate 6-sulfate (1), -phosphonate (2), -fluorophosphonate (3) and –boronate (4) groups in place of the 6-phosphate moiety of the substrate. The inhibitory efficacies of these adducts were evaluated against trehalose 6-phosphate phosphatases selected from evolutionarily distant pathogenic bacteria and nematodes. Phosphonates 2 and 3 were found to display good inhibitory activities against the T6PPs, while the sulfate analog, trehalose-6-sulfate, proved to be a particularly effective broad-spectrum inhibitor of these phosphatases and an ideal prototype for optimization.     

Synthesis of indole-containing analogs of (1R)-cis-chrysanthemic acid and N-substituted (1R)-cis-chrysanthemylamines

The indolic analogs of (1R)-cis-chrysanthemic acid and N-substituted (1R)-cis-chrysanthemylamines were obtained by Fischer indole synthesis using the acetonylcyclopropanes derived from (+)-car-3-ene. The cyano- and N-cyanamido groups in the starting carbonyl compounds did not hinder indolization. The reduction of the nitrile group bound to the asymmetrical atom of the cyclopropane ring by LiAlH₄ in ether can be accompanied by epimerization or racemization.     

Crystal structure of 17-oxo-5α-androstano [3,4-C] 1′2′5′-oxadiazole (HS1000)

The title compound (C₁₉H₂₆N₂O₂) is one of a series of novel heteroatom steroidal derivatives recently prepared for testing their antifertility profiles and progesterone binding affinity. It is one of a pair of epimers differing in configuration at position 5. The X-ray analysis has uniquivocally resolved this ambiguity. The compound crystallizes in space group P2₁2₁2₁, a = 9.257(3), b = 9.419(3), c = 19.089(5)Å, and Z = 4 and the structure was solved by direct methods. In the steroid skeleton Ring A does not exhibit the chair conformation commonly found in the steroid nucleus, being considerably strained, presumably as a consequence of the fused planar oxadiazole ring E. Rings B and C, however, are chairs and ring D is in an intermediate envelope/half-chair conformation. All rings of the steroid skeleton are trans connected.