Improved Syntheses of Indole-3-aldehyde

Design and synthesis of an indol derivative as antibacterial agent against Staphylococcus aureus

Several indole derivatives with antibacterial activity have been prepared using different protocols; however, some require special reagents and conditions. The aim of this study involved the synthesis of some indole derivatives using estrone and OTBS-estrone as chemical tools. The synthesis of the indole derivatives involves reactions such as follows: (1) synthesis of two indol derivatives (4 or 5) by reaction of estrone or OTBS-estrone with phenylhydrazine in medium acid; (2) reaction of 4 or 5 with 6-cloro-1-hexyne in medium basic to form two hexynyl-indol (7 or 8); (3) preparation of indol-propargylic alcohol derivatives (10 or 11) by reaction of benzaldehyde with 7 or 8 in medium basic; (4) synthesis of indol-aldehydes (12 or 13) via oxidation of 10 or 11 with DMSO; (5) synthesis of indeno-indol-carbaldehyde (15 or 16) via alkynylation/cyclization of 12 or 13 with hexyne in presence of copper(II); (6) preparation indeno-indol-carbaldehyde complex (19 or 20) via alkynylation/cyclization of 12 or 13 with 1-(hex-5-yn-1-yl)-2-phenyl-1H-imidazole. The antibacterial effect exerted by the indol-steroid derivatives against Streptococcus pneumoniae and Staphylococcus aureus bacteria was evaluated using dilution method and the minimum inhibitory concentration (MIC). The results showed that only the compound 19 inhibit the growth bacterial of S. aureus. In conclusion, these data indicate that antibacterial activity of 19 can be due mainly to functional groups involved in the chemical structure in comparison with the compounds studied.

An efficient approach to 1,2,3-trisubstituted indole via rhodium catalyzed carbene Csp3–H bond insertion

A method for convenient synthesis of N-alkyl-2-aryl-indole-3-carbaldehyde via carbene C–H bond insertion.

Investigation of the in vitro antioxidant behaviour of some 2-phenylindole derivatives: discussion on possible antioxidant mechanisms and comparison with melatonin

Oxidative stress has been implicated in the development of many neurodegenerative diseases and also responsible from aging and some cancer types. Indolic compounds are a broad family of substances present in microorganisms, plants and animals. They are mainly related to tryptophan metabolism, and present particular properties that depend on their respective chemical structures. Due to free radical scavenger and antioxidant properties of indolic derivatives such as indolinic nitroxides and melatonin, a series of 2-phenyl indole derivatives were prepared and their in vitro effects on rat liver lipid peroxidation levels, superoxide formation and DPPH stable radical scavenging activities were determined against melatonin, BHT and alpha-tocopherol. The compounds significantly inhibited (72-98%) lipid peroxidation at 10(-3) M. These values were similar to that observed with BHT (88%). Possible structure-activity relationships of the compounds were discussed.

Synthesis and Antioxidant Activity of New Tetrahydro-Naphthalene-Indole Derivatives as Retinoid and Melatonin Analogs

A number of retinoid-related compounds represent classes of antioxidative and proapoptotic agents with promising potential in the treatment of neoplastic diseases. Indeed, the synthetic retinoid amide fenretinide [N-(4-hydroxyphenyl)retinamide] induces apoptosis of cancer cells and acts as a chemotherapeutic drug in cancer therapy. In the present work, and as a continuation of our studies on retinoid-type compounds, the synthesis of melatonin retinamide derivatives was studied as a novel series of melatonin retinoids, using the condensation reaction sequence involving tetrahydrotetramethylnaphthalene carboxylic acid and appropriate melatonin-type moieties. Despite of the weak DPPH inhibition activity pattern of the synthesized compounds, some of them showed a strong inhibition on lipid peroxidation (IVa-b, Va, and VIIa-c, 88, 96, 90, 94, 93, and 86%, respectively at 10(-4) M concentration) when melatonin (85% at 10(-4) M concentration) was used as a reference compound.

Vilsmeier formylation of 2-carboxyindoles and preparation of O-benzylhydroxyureas on solid phase

The Vilsmeier formylation has been introduced for the solid-phase functionalization of five different 2-carboxyindoles. The aldehyde functionality has been utilized in the preparation of O-benzylhydroxyureas.

Unusual synthesis of new glycine antagonists via sequential aldol condensation-lactonization-elimination reaction

Compounds 2 and 3 were designed in order to probe the North-East region of the strichnine-insensitive glycine binding site of the NMDA receptor. The two products were obtained readily by a tandem aldol condensation-lactonization-elimination step which affords the desired E isomer with complete regioselection.

3-(Octadecanoylaminomethyl)indole-2-carboxylic acid derivatives and 1-methyl-3-octadecanoylindole-2-carboxylic acid as inhibitors of cytosolic phospholipase A2

3-(1-Acylaminooctadecyl)indole-2-carboxylic acids and 3-(1-acylaminooctadecyl)-1-methylindole-2-carboxylic acids were designed and synthesized as inhibitors of cytosolic phospholipase A2. Enzyme inhibition was assayed by evaluation of calcium ionophore A23187-induced arachidonic acid release from bovine platelets. While compounds with 1-octadecanoylaminooctadecyl groups in position 3 of the indole were inactive inhibition data for 3-[1-(3-phenylpropionylamino)octadecyl]indole-2-carboxylic acids could not be evaluated because of lysis of the platelets. However 3-(octadecanoylaminomethyl)indole-2-carboxylic acid derivatives and 1-methyl-3-octadecanoylindole-2-carboxylic acid proved to be inhibitors of cytosolic phospholipase A2. The most active inhibitor was the latter compound with an IC50 of 8 microM.