Formal synthesis of ( − )-pereniporin B and ( − )-cinnamosmolide

Abstract

The paper describes a new pathway for an efficient synthesis of natural and bioactive drimanic compounds ( - )-pereniporin B (1) and ( - )-cinnamosmolide (2) from ketodiol 7, an intermediate obtained before from accessible labdane diterpenoid (+)-larixol (3). The key step involves allylic bromination of acetate 8 with N-bromosuccinimide. The in vitro antimicrobial and antifungal activities of all compounds are also reported. Their structures were confirmed by both spectroscopic data and chemical transformations.

Sex Pheromone of the Invasive Mealybug Citrus Pest, Delottococcus aberiae (Hemiptera: Pseudococcidae). A New Monoterpenoid with a Necrodane Skeleton

“…The functionalization of the enone methyl group via the allylic bromination of ketone 3 using NBS in DCM under irradiation , gave bromo ketone 4 as the main product with a 65% yield (in some experiments, the α-keto dibrominated product was also identified by the GC-MS analysis in variable amounts as a byproduct, which proved unstable after isolation by column chromatography and decomposed in a few hours). The crude bromo ketone 4 was treated with potassium acetate in DMSO , to afford acetate 5 with an overall 60% yield starting from ketone 3 . The alkylation of the allylic acetate, with methyl iodide using LDA and THF as base, provided ketone 6 with a low yield of 43%.…”