Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

In this review we present relevant and recent applications of porphyrin derivatives as photocatalysts in organic synthesis, involving both single electron transfer (SET) and energy transfer (ET) mechanistic approaches. We demonstrate that these highly conjugated photosensitizers show increasing potential in photocatalysis since they combine both photo- and electrochemical properties which can substitute available metalloorganic photocatalysts. Batch and continuous-flow approaches are presented highlighting the relevance of enabling technologies for the renewal of porphyrin applications in photocatalysis. Finally, the reaction scale in which the methodologies were developed are highlighted since this is an important parameter in the authors' opinion.

Sedative Effect of Monoterpene Alcohols in Mice: A Preliminary Screening

Many essential oils and monoterpenes are used therapeutically as relaxing drugs and tranquilizers. In this study, ten structurally related monoterpene alcohols, present in many essential oils, were evaluated in mice to investigate their pharmacological potential in the central nervous system. Isopulegol (1), neoisopulegol (2), (±)-isopinocampheol (3), (-)-myrtenol (4), (-)-cis-myrtanol (5), (+)-p-menth-1-en-9-ol (6) and (±)-neomenthol (8) exhibited a depressant effect in the pentobarbital-induced sleep test, indicating a sedative property. (-)- Menthol (7), (+)-dihydrocarveol (9), and (±)-isoborneol (10) were ineffective in this test. The results show that these psychoactive monoterpenes have the profile of sedative drugs, and this pharmacological effect is influenced by the structural characteristics of the molecules

Antinociceptive Profile of 2-Phenylselenenyl-1,8-cineole in Mice

2-Phenylselenenyl-1,8-cineole (PSC) increased both the pentobarbital-induced sleeping time and the reaction time (up to 2 h) in the tail immersion method. PSC also caused dose-dependent inhibition of acetic acid induced writhing with maximum inhibition of 93.4% and was approximately 8.5-fold more potent than 1,8-cineole. These findings show that PSC presents sedative effect and significant antinociceptive activity.

Oxime derivatives with larvicidal activity against Aedes aegypti L

Oximes containing secondary metabolites constitute an important group of bioactive compounds and have been described and frequently updated in the literature due to their pharmacological properties. Thus, the aim of this study was to evaluate the larvicidal activity of a series of fourteen structurally related [1,4]-Benzoquinone mono-oximes on third-instar Aedes aegypti larvae and to investigate structure-activity relationships (SAR) of these compounds. Results of larvicidal assay revealed that all oximes were found to have larvicidal activity. Compound 2,6-dimethyl-[1,4]-benzoquinone oxime tosylate (11) was the most bioactive (LC50 = 9.858 ppm), followed by 2-methyl-[1,4]-benzoquinone oxime tosylate (9) (LC50 = 14.450 ppm). [1,4]-benzoquinone oxime (1) exhibited the lowest potency, with an LC50 = 121.181 ppm. The molecular characteristics which may help to understand the assayed compounds larvicidal activity were identified. SAR indicates that the addition of alkyl groups attached to the ring, number, position in the unsaturated cyclic structure, and size of these groups influence the larvicidal activity. Moreover, the lipophilicity seems to play an important role in increasing the larvicidal effect, because, in general, tosyl-containing products were more potent than products containing free OH.

Analysis of a cycloheptenone derivative: an experimental and theoretical approach

A detailed analysis with total assignment of (1)H and (13)C NMR spectral data for a cycloheptenone derivative, a key intermediate for the synthesis of perhydroazulene terpenoids, is related. These assignments are based on 1D (1)H and (13)C NMR and on 2D NMR techniques including gCOSY, gHSQC, gHMBC, J-resolved and NOEDIF experiments. The unequivocal assignments were supported by theoretical chemical shifts and scalar coupling constant calculations at GIAO B3LYP/cc-pVDZ level from optimized structures at the same level of theory.

Structural studies on the dichlorocarbene adducts with (−)-R-carvone. I. The crystal structures of [1R, 4R, 6R, 9R]-7,7-dichloro-1-methyl-4-[2′,2′-dichloro-1′-methyl- cyclopropyl]-bicyclo[4.1.0]-heptan-2-one and [1R, 4R, 6R, 9S]-7,7-dichloro-1-methyl-4-[2′,2′-dichloro-1′-methylcyclopropyl]-bicyclo[4.1.0]-heptan-2-one

The crystal structures of the title compounds have been determined from diffractometric X-ray data and refined by full-matrix least-squares to final R factors of 0.047 and 0.060 from 830 and 620 independent reflections above background, respectively. The space group and the number of molecules per unit cell are the same in both cases: P212121 and Z = 4. Cell dimensions are: a = 7.982(2), b = 9.538(3), c = 18.785(3) Å for the S form and a = 10.339(3), b = 11.510(3), and c = 11.886(6) Å for the R form. The molecules, produced simultaneously in the same chemical reaction, have essentially identical configuration except for the location of the chlorine atoms at C-11 (in the S case) and at C-10 (in the R case). This difference gives rise to a completely different molecular packing of the structures. In each compound the two cyclopropane rings present a cis relationship to one another, with an identical dihedral angle of 77.0°.

Regio-and Stereoselective Ring Opening of Epoxides with Sodium Phenylselenide under Phase Transfer Conditions

The ring opening reaction of a wide range of mono-, di- and trisubstituted epoxides with the phenylselenide anion under PTC conditions provides a simple, mild and efficient method for preparation of β-hydroxy phenylselenides with high regio- and stereoselectivity in yields from 67 to 98%. The reactions are carried out in aqueous NaOH/ THF using aminoiminomethanesulfinic acid (thiourea dioxide, TDO) to generate sodium phenylselenide from diphenyldiselenide.

Diverse Continuous Photooxygenation Reactions of (+) and (-)-α-Pinenes to the Corresponding Pinocarvones or trans-Pinocarveols

In this study, the continuous photooxygenation reactions of (+) and (-)-α-pinenes are described. The corresponding hydroperoxides were continuously processed under mild conditions using Ac2O and base to yield (-) or...