Monica F. Z. J. Amaral

Queen signals in a stingless bee: suppression of worker ovary activation and spatial distribution of active compounds

In most species of social insect the queen signals her presence to her workers via pheromones. Worker responses to queen pheromones include retinue formation around the queen, inhibition of queen cell production and suppression of worker ovary activation. Here we show that the queen signal of the Brazilian stingless bee Friesella schrottkyi is a mixture of cuticular hydrocarbons. Stingless bees are therefore similar to ants, wasps and bumble bees, but differ from honey bees in which the queens signal mostly comprises volatile compounds originating from the mandibular glands. This shows that cuticular hydrocarbons have independently evolved as the queens signal across multiple taxa, and that the honey bees are exceptional. We also report the distribution of four active queen-signal compounds by Matrix-assisted laser desorption/ionization (MALDI) imaging. The results indicate a relationship between the behavior of workers towards the queen and the likely site of secretion of the queens pheromones.

Directed metalation of 1-ester-substituted indolizines: base/electrophile-controlled regioselective functionalization.

A variety of C-2 and C-5 difunctionalized indolizines have been prepared through the reaction of 1-ester-substituted indolizines with organometallic bases followed by a reaction with different electrophiles. Metalation takes place under mild conditions allowing the isolation of a number of difunctionalized indolizines in good yields. The regioselectivity of the reaction appears to be governed by the nature of the base and electrophile.

Application of the Negishi reaction in the synthesis of thiophene-based lignans analogues with leishmanicidal effects

As lignanas tetraidrofurânicas sao metabolitos secundarios com reconhecida atividade antiprotozoaria. Na literatura, ha varios relatos sobre os efeitos anti-parasitarios de analogos sinteticos de lignanas contendo pontes de enxofre. Neste trabalho, foi realizada a sintese de analogos tiofenicos de lignanas com o uso de uma estrategia sintetica seletiva e de alto desempenho baseada na reacao de acoplamento cruzado de Negishi. Os derivados sinteticos foram obtidos de maneira rapida e apresentaram alto grau de pureza e baixa toxicidade para uma linhagem celular de mamifero e atividade leishmanicida com diferentes potencias. Lignans represent a well-known group of natural products with anti-protozoal activity. In the literature there are many examples of the anti-parasitic activity of synthetic analogues of lignans containing sulphur bridges. In this work, we have obtained thiophene-based analogues by using a selective and high performance synthetic strategy based on the Negishi cross-coupling reaction. The derivatives were quickly obtained and showed great purity, low toxicity toward a mammalian cell line, and leishmanicidal activity with different potencies.

1-Benzoyl-5-phenyl-2-(propan-2-yl)-1,2,3,4-tetra­hydro­pyrimidin-4-one

The tetrahydropyrimidinone ring in the title compound, C20H20N2O2, is in a half-boat conformation with the N—C—N C atom 0.580 (2) Å out of the plane defined by the remaining five atoms. In the crystal structure, molecules are connected into centrosymmetric dimers via N—H⋯O interactions. The dimeric aggregates are linked into supramolecular chains along the a axis via C—H⋯π interactions.