Synthesis of a novel series of 2-methylsulfanyl fatty acids and their toxicity on the human K-562 and U-937 leukemia cell lines

Enhancing the Extent of Enolization for α-C-H Bonds of Aliphatic Carboxylic Acid Equivalents via Ion Pair Catalysis: Application toward α-Chalcogenation

In general, the α-functionalization of carboxylic acid derivatives requires either a transition metal catalyst or a stoichiometric activating agent/strong base/external additive. A transition metal free α-chalcogenation of aliphatic carboxylic acid equivalents is reported herein via ion pair formation using K₃PO₄ as a catalyst. Mild conditions, broad scope, scalability of the process, attaining bioactive glucokinase activators, and some synthetic intermediates establish merits of the strategy.

Catalytic Approaches for the Direct Heterofunctionalization of Aliphatic Carboxylic Acids and Their Equivalents with Group 16 Elements

In contrast to traditional multistep synthesis, modern organic synthesis extensively depends on the direct functionalization of unactivated C-H bonds for the construction of various C-C and C-heteroatom bonds in atom- and step-economic manner. Common aliphatic substrates, e. g. carboxylic acids and their synthetic equivalents, are regiospecifically functionalized based on either a directed approach, in which the polar directing group assists to functionalize a specific C-H bond positioned at β- and γ-carbon centers, or a non-directed approach typically leading to α-functionalization. While numerous reviews on catalytic C-H functionalization have appeared, a concise review on the direct C(sp³ )-H heterofunctionalization of carboxylic acid synthons with Group 16 elements has been awaited. The recent advances on the direct oxy-functionalization and chalcogenation of aliphatic carboxylic acid synthons enabled by transition metal, organo- and photocatalysts are described herein.

The (5Z)-5-Pentacosenoic and 5-Pentacosynoic Acids Inhibit the HIV-1 Reverse Transcriptase

The natural fatty acids (5Z)-5-pentacosenoic and (9Z)-9-pentacosenoic acids were synthesized for the first time in eight steps starting from either 4-bromo-1-butanol or 8-bromo-1-butanol and in 20-58% overall yields, while the novel fatty acids 5-pentacosynoic and 9-pentacosynoic acids were also synthesized in six steps and in 34-43% overall yields. The ∆(5) acids displayed the best IC50's (24-38 µM) against the HIV-1 reverse transcriptase (RT) enzyme, comparable to nervonic acid (IC50 = 12 µM). The ∆(9) acids were not as effective towards HIV-RT with the (9Z)-9-pentacosenoic acid displaying an IC50 = 54 µM and the 9-pentacosynoic acid not inhibiting the enzyme at all. Fatty acid chain length and position of the unsaturation was important for the observed inhibition. None of the synthesized fatty acids were toxic (IC50 > 500 µM) towards peripheral blood mononuclear cells. Molecular modeling studies indicated the structural determinants underlying the biological activity of the most potent compounds. These results provide new insights into the structural requirements that must be present in fatty acids so as to enhance their inhibitory potential towards HIV-RT.

Synthesis of the novel (±)-2-methoxy-6-icosynoic acid--a fatty acid that induces death of neuroblastoma cells

The first total synthesis for the novel fatty acid (±)-2-methoxy-6-icosynoic acid was accomplished in seven steps and in a 14% overall yield starting from 2-(4-bromobutoxy)-tetrahydro-2H-pyran. The title compound displayed an EC50=23±1 μM against the human SH-SY5Y neuroblastoma cell line and an EC50=26±1 μM against the human adenocarcinoma cervix cell line (HeLa) after 48 h of exposure. The corresponding non-methoxylated analog 6-icosynoic acid did not display cytotoxicity (EC50>500 μM) toward the studied cell lines as well as the 2-methoxyicosanoic acid (EC50>300 μM). The critical micelle concentration (CMC=20-30 μM) for the (±)-2-methoxy-6-icosynoic acid was also determined. It was found that α-methoxylation decreases the CMC of a fatty acid.