Collection periods in the in vitro establishment of raspberry tree cultivars

The raspberry tree, a species from the Rosaceae family and the Rubus genus, is included in the group of small fruit that has been drawing the attention of the global consuming market for carrying antioxidant properties and substances capable of fighting free radicals, bringing health benefits. The objective of this work was to evaluate the effect of collection periods on the in vitro establishment of raspberry trees (Rubus idaeus L.). Explants were collected in different seasons of the year (winter, spring, summer and autumn), and were inoculated in a MS culture medium. The experimental design was totally randomized, and arranged in a factorial scheme. At 28 days, the following variables were evaluated: oxidation, fungal and bacterial contamination survival and establishment. There was less phenolic oxidation in raspberry tree explants collected in winter. Explants contamination by endogenic bacteria occurred in higher percentages in winter. Although summer was the season of the year with higher percentage of explants’ phenolic oxidation for both cultivars, the highest in vitro establishment percentages for the Heritage cultivar occurred in summer and fall. However, for the Fallgold cultivar, spring and winter were the seasons with greater in vitroestablishment.

Efforts Toward a Synthesis of Crotogoudin and Crotobarin

Two synthesis designs for the diterpenoid crotogoudin are discussed, and efforts to achieve each are described. First, a Cope rearrangement/intramolecular Diels–Alder cascade reaction was investigated. Second, a bioinspired sequence of cationic bicyclization and A-ring oxidative fragmentation set-up for a lactonization induced by a phenolic oxidation, ultimately providing a tricyclic intermediate that required only installation of the bridging ring of the salient bicyclo[2.2.2]octane system. This last endeavor was fraught with difficulty, but did lead to the development of conditions for cyclization of related keto-alkenes via manganese(III)-based radical chemistry.

Multicomponent access to indolo[3,3a-c]isoquinolin-3,6-diones: formal synthesis of (±)-plicamine

The complete tetracyclic core structure of plicamine, a novel Amaryllidaceae-type alkaloid, was expeditously prepared by an Ugi four-component condensation reaction, followed by a one-pot sequential phenolic oxidation and intramolecular coupling process.