The use of bis(pyridine)iodonium tetrafluoroborate (IPy(2)BF(4)) as an oxidizing agent towards different types of alcohols is reported. The observed reactivity involves different reaction pathways, as a function both of the structures of the starting materials and of the experimental conditions. Interestingly, the title iodine-containing compound is capable of a tuneable reaction with simple cycloalkanols, providing straight and selective access either to omega-iodocarbonyl compounds or to ketones, a previously unreported and chemoselective range of oxidation potential. Furthermore, appropriate conditions for the preparation of aldehydes and esters from primary alcohols by easily performed experimental procedures were also established. The beta-scission reactions of cycloalkanols and the alpha-oxidation processes of primary, secondary and benzylic alcohols are discussed.
The preparation of N-methylpyrazoles is usually accomplished through reaction of a suitable 1,3-diketone with methylhydrazine in ethanol as the solvent. This strategy, however, leads to the formation of regioisomeric mixtures of N-methylpyrazoles, which sometimes are difficult to separate. We have determined that the use of fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as solvents dramatically increases the regioselectivity in the pyrazole formation, and we have used this modification in a straightforward synthesis of fluorinated analogs of Tebufenpyrad with acaricide activity.
A small library of compounds with an oxa(thia)zole scaffold and structural diversity in both positions 2 and 5 has been synthesized. Double acylation of a protected glycine affords intermediate alpha-amido-beta-ketoesters, which in turn can be dehydrated to afford 1,3-oxazoles or reacted with Lawesson's reagent to furnish 1,3-thiazoles. This procedure was designed with its adaptation to fluorous techniques in mind. Thus, when a protected glycine with a fluorous tag in the ester moiety is used as a starting material, the synthesis can be easily completed without column chromatography purification of intermediate compounds with good to excellent yields, thus affording a suitable entry to the preparation of small libraries of these bioactive compounds. The prepared oxa(thia)zoles were assayed for their antibacterial activity, and several of them were active against Staphylococcus aureus.
Neutral and cationic series of new trimeric b-hydroxy amino or ammonium surfactants were synthesized via a two-step process involving the Williamson etherification and regioselective oxirane ring opening with primary and tertiary amines, which afforded good to excellent yields. The synthesized compounds were obtained in high purity by a simple purification procedure on column chromatography. The critical micelle concentration (CMC), effectiveness of surface tension reduction (c CMC ), surface excess concentration (C), and area per molecule at the interface (A) were determined and values indicate that the cationic series is characterized by good surface-active and self-aggregation properties. The antimicrobial activities are reported for the first time against representative bacteria and fungi for trimeric compounds. The antimicrobial potency was found to be dependent on the target microorganism (Gram-positive bacteria [ fungi [ Gram-negative bacteria), as well as both the neutral or ionic nature (cationic [ neutral) and alkyl chain length (tri-C 12 [ tri-C 18 [ tri-C 8 ) of the compounds. The tri-C 8 and tri-C 18 compounds were found to be almost inactive and the tri-C 12 compounds, the most potent antimicrobial surface-active agents from the synthesized series. The trimeric C 12 cationic compound was found to be comparable to benzalkonium chloride against Gram-positive bacteria and fungi, in vitro. The antimicrobial effectiveness of this new compound and the facile two-step procedure for synthesizing it with an excellent overall yield (92%) provide a cost effective trimeric gemini surfactant.
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