BF3·OEt2-Catalyzed Rearrangement of Epoxy-Himachalenes: Access to New Biosourced N-Acetamide-Based Himachalenes

Abstract

Biosourced N-acetamide-based himachalenes were synthesized by Lewis acid catalyzed rearrangement of epoxy-himachalene derived from α-cis- and β-himachalenes, the main component of essential oil of Atlas cedar (Cedrus atlantica). Several new chiral polycyclic N-acetamide compounds were obtained with different selectivities depending on the acid used. Among the Lewis acids used, BF3·OEt2 under catalytic and mild conditions is efficient and selective affording the formation of chiral N-acetamides in good yields. Otherwise, using acetonitrile as solvent and reagent was proved as an efficient tool giving access to new N-acetamide-based himachalenes. A mechanism to explain the formation of the different compounds observed in the reaction mixture has also been proposed.

Synthesis and Evaluation of Antimicrobial Activity of the Rearranged Abietane Prattinin A and Its Synthetic Derivatives

“…In this study, we examined this reaction in the presence of I 2 , which now serves as a catalyst, while changing the solvent to dimethyl sulfoxide (DMSO). (10), 23 (15) In this study, the use of 5% of I 2 at room temperature resulted in a single aromatic product 21 with a 92% yield after 7 days (Entry 2). Increasing the temperature to 70 • C under the same conditions as before, the reaction resulted in complete conversion after 9 h, with the formation of two products: aromatic compounds 21 (80%) and 17 (20%) (Entry 3).…”

“…Subsequently, the oxidation of compound 24 with (PhSeO) 2 O (see Reference [7]) resulted in complete conversion, yielding orthoquinone 25 and hydroxy dienone 26, respectively, in 78% and 19% yields (Scheme 2). The action of a Brønsted acid such as p-toluenesulfonic acid (PTSA) [15] on orthoquinone-ester 25 in anhydrous benzene led, after 7 h, to the formation of 6-deoxytaxodione derivative 27 [16], with a yield of 52%.…”