Synthesis of (±) debenzoyl analogs of norsampsones as potential anticancer agents

Total Synthesis of Norsampsones A and B, Garcinielliptones N and O, and Hyperscabrin A

“…On the other hand, decarbonyl PPAPs or related compounds also may be used as building blocks for the synthesis of PPAPs and their derivatives (Scheme ). Although great interest is evident in the synthesis of PPAPs, only one achiral synthetic study of the decarbonyl PPAPs toward the norsampsones and their analogues has been reported . On the other hand, for many of these natural products, their absolute configuration is still not determined or has been achieved by the analysis of circular dichroism spectra.…”

“…8a Although great interest is evident in the synthesis of PPAPs, only one achiral synthetic study of the decarbonyl PPAPs toward the norsampsones and their analogues has been reported. 14 On the other hand, for many of these natural products, their absolute configuration is still not determined or has been achieved by the analysis of circular dichroism spectra. It is very desirable to develop asymmetric synthesis procedures to confirm compounds with their absolute configurations.…”

Total synthesis and structural reassignment of garcinielliptone FC, a polycyclic polyprenylated acylphloroglucinol with diverse bioactivity

“…We decided to use the Dieckmann reaction strategy that Plietker used to prepare a series of type B PPAPs with endo C-7 substituents. 39 a First, following a precedent described in Shibasaki's synthesis of garsubellin A, Stork–Danheiser reaction of commercially available 5 with prenyl bromide afforded cyclohexenone 6 (Scheme 1), 34 a ,42,43 which was further converted to β-ketoester 7 (dr = 2 : 1) in 81% yield by treatment with LDA and methyl cyanoformate. Meanwhile, ethyl acetoacetate was alkylated with iodide 8 to give β-ketoester 9 , and temporary protection of the ketone of 9 , reduction of the ester group to the alcohol, and acid-catalyzed deprotection of the ketone and dehydration gave α,β-unsaturated ketone 10 in 76% yield.…”

Structural Revision of Hyperibrin B and Hyperscabrones H and I by Biosynthetic Considerations, NMR Analysis, and Chemical Synthesis

“…In order to confirm our revision of HB’s structure to 1a , we undertook a concise total synthesis of (±)- 1a (Schemes and ) that was inspired by Shibasaki’s and Yang’s synthetic routes to garsubellin A and norascyronones A and B. , Specifically, Stork–Danheiser reaction of 3-ethoxy-2-cyclohexenone 3 afforded the prenylated enone 4 in 83% yield. ,, Methylation of 4 , by treating with lithium diisopropylamide (LDA) followed by methyl iodide, gave compound 5 as a single diastereomer in 81% yield as reported by Yang et al, and its spectral data matched with those in the literature . We initially wanted to introduce the hydroxyl first and subsequently install the prenylmethyl and acyl groups, so we subjected 5 to Rubottom oxidation, which gave the ketol 6 (56% overall) with the desired diastereoselectivity .…”