Use of Conjugated Dienones in Cyclialkylations:  Total Syntheses of Arucadiol, 1,2-Didehydromiltirone, (±)-Hinokione, (±)-Nimbidiol, Sageone, and Miltirone

Abstract

Functionalized hydrophenanthrenes can be prepared using a cyclialkylation-based strategy. These annulations are highly dependent on the directing effects of the arene substitutents and on conformational considerations. The utility of this methodology was featured in the syntheses of six diterpenoids.

Total synthesis of 1-oxomiltirone via Suzuki coupling

“…9 Furthermore, the additional application could synthesize miltirone by the reduction of the ketone group in 6, 5 de-methylation of the methyl ether and the subsequent Dess-Martin oxidation. 4 In conclusion, we have developed a short synthesis route to versatile intermediate 6 via Suzuki coupling as a key reaction.…”

“…2 Due to their important activities, research has focused on the total syntheses of these compounds. [3][4][5] In our endeavor to modify bioactive abietane diterpenes for medical purposes, we found that compound 6 was a key intermediate to accomplish total synthesis of xanthoperyl methyl ether 2 and pisiferic acid 5.…”

“…Alternatively, the same skeleton of 6 could be constructed through annulation strategy of 2-aryl dienone reported by Majetich 5 . This was derived from an aromatic metal nucleophile ring-opening of silyl enol epoxide, and a vinyl addition with a subsequent PDC oxidative rearrangement.…”

Synthesis of 6,7-benzo-3-borabicyclo[3.3.1]nonane and its 3-aza analog from 2-allylphenyl(diallyl)borane. Intramolecular arylboration of the C=C bond

“…2 Allyl bromobenzene 4 was prepared according to procedures described earlier. 13,14 Dimethyl 2 allylphenylboronate (5). A solution of 4 (10.23 g, 41 mmol) in THF (50 mL) was added to magnesium chips (1.1 g, 45 mmol) activated with 1,2 dibromoethane in THF (20 mL).…”

Chemoselective reaction of ethane-1,2-dithiol, hydrazines, and hydroxylamine onto γ-keto allyl phosphonates and phosphine oxides

“…[13][14][15] On the basis of these unsuccessful preliminary results, we decided to first establish the suitable experimental conditions for the protection of the ketone moiety of the ketophosphonate 1a using ethylene glycol or ethane-1,2-dithiol commonly used for this purpose. At the same time, we envisionned to explore the reaction of other N-nucleophiles including hydrazines, tosylhydrazines, [16][17][18][19][20][21][22][23][24] and hydroxylamine 25-31-32-33 on the enone moiety. Hence, we wish to report in this paper our results on the chemoselective reaction of these Sand N-nucleophiles on a series of γ-keto allyl phosphonates.…”