Both Rosa roxburghii and R. sterilis, belonging to the Rosaceae, are endemic species in Guizhou Province, China. The fruits of these two species are mixed-used as functional food in the region. Aiming to elucidate the phytochemical characteristics of R. roxburghii and R. sterilis fruits, the essential oils and constituents in a methanol extract have been analyzed and compared by GC-MS and UFLC/Q-TOF-MS, respectively. As a result, a total of 135 volatile compounds were identified by GC-MS and 91 components were different between R. roxburghii and R. sterilis fruits; a total of 59 compounds in methanol extracts were identified by UFLC/Q-TOF-MS, including 13 organic acids, 12 flavonoids, 11 triterpenes, nine amino acids, five phenylpropanoid derivatives, four condensed tannins, two stilbenes, two benzaldehyde derivatives and one benzoic acid derivative; and nine characteristic compounds were found between R. roxburghii and R. sterilis fruits. This systematic study plays an important role for R. roxburghii and R. sterilis fruits in the product development.
The cyrneine diterpenoids represent a structurally intriguing subfamily of cyathane diterpenoids and could significantly induce neurite outgrowth. Therefore, the efficient synthesis of these natural products is of great importance. Herein, we present a route for the collective synthesis of cyrneines A, B, and glaucopine C. As the key precursor, the 5-6-6-tricyclic scaffold is efficiently constructed by employing a mild Suzuki coupling of heavily substituted nonactivated cyclopentenyl triflate and a chelation-controlled regiospecific Friedel-Crafts cyclization as key transformations. The stereoselective installation of the all-carbon quaternary center at C6 ring junction of the tricycle is achieved via Birch reductive methylation. Subsequently, a carbenoid-mediated ring expansion furnishes the essential 5-6-7-tricyclic core. Finally, manipulation of this core by several appropriately orchestrated conversions accomplishes a more step-economic synthesis of cyrneine A (20 steps), and the first synthesis of cyrneine B (24 steps) and glaucopine C (23 steps).
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