Synthesis of Cyclosiphonodictyol A and Its Bis(sulfato)

Abstract

The first synthesis of the marine benzoxepane hydroquinone cyclosiphonodictyol A and its bis­(sulfato) from commercial (+)-sclareolide is reported. The key steps of the synthetic sequence (11 steps, 46% global) are the nucleophilic attack of a hindered tertiary alkoxide, a ring-closing metathesis reaction, and the Diels–Alder cycloaddition of a dienol acetate.

Marine natural products

“…500 A number of terpenoids and steroids were also synthesised for the rst time in 2020. [501][502][503][504][505] In what may be a world rst, three Australian groups have independently reported the reassignment of the same class of sponge metabolite; all three publications were received at the respective journal editorial offices within four months of each other in late 2019, and all were published in January or early February of 2020. Reinspection of the NMR data of echinosulfone A suggested the originally published structure may be incorrect.…”

A General Strategy for the Construction of Calyciphylline A‐Type Alkaloids: Divergent Total Syntheses of (−)‐Daphenylline and (−)‐Himalensine A

“…Although a wide variety of conditions were screened, including a cascade Diels-Alder reaction of norbornadiene and diene 24 followed by retro-Diels-Alder elimination of cyclopentadiene and oxidative aromatization, none of these reactions afforded the desired aromatization product. Inspired by a valuable precedent, [25] an efficient Diels-Alder/aromatization leading to 26 (77 %) was accomplished by heating diene 24 and trans-1,2bis(phenylsulfonyl)ethylene 25 at 150 8C in toluene in a stainless steel autoclave followed by one-pot elimination of the phenylsulfonyl groups using DBU. Interestingly, the reaction intermediates can be isolated if desired.…”