Structural Revision of Guttiferone F and 30-epi-Cambogin

Abstract

Guttiferone F, a natural polyprenylated polycyclic acylphloroglucinol, was originally assigned as the 30-epimer of garcinol by NMR data analyses. Conversion of guttiferone F in the presence of acid afforded its cyclized form (2a), which was previously assigned as 30-epi-cambogin. However, the absolute configurations of guttiferone F and 2a have not been determined. Reinvestigation of the structures of those two compounds, using X-ray and NMR data analyses and chemical transformation, revealed that the original assignment of the C-30 absolute configuration in guttiferone F and 2a should be inverted. Guttiferone F is indeed garcinol, and 2a, which was previously identified as 30-epi-cambogin, is cambogin.

Polyprenylated Acylphloroglucinols With Different Carbon Skeletons From the Fruits of Garcinia multiflora

“…Recently, the absolute configuration of C-23 of the isogeranyl of PPAPs bearing exocyclic stereocenters such as guttiferone F has been determined and revised by total synthesis and X-ray diffraction, and a preliminary conclusion has been drawn that BPAP-bearing exocyclic stereocenters from natural sources mostly carries S configuration of the isogeranyl. According to this rule, all (23 R )- endo -type B BPAPs with a isogeranyl at C-5 are corrected to be (23 S )- endo -type B BPAPs, including garcimultiflorones D–F, 18-hydroxygarcimultiflorone D, isogarcimultiflorone F, and garcimultiflorone J isolated from the same plant ( Wang et al, 2021 ; Zheng et al, 2021 ). Combined with the biosynthetic pathway and this rule, the configuration of C-23 could be tentatively determined as S* .…”

Polyprenylated Benzophenones and Tocotrienol Derivatives from the Edible Fruits of Garcinia oblongifolia Champ. ex Benth. and Their Cytotoxicity Activity

“…uration of the chiral side chains. According to the lastest reported literature,41,42 researchers inferred that the natural compounds are most likely to have an (S)-lavandulyl group, which provided valuable references for configurational determination of the chiral side chains, such as the lavandulyl group of 4. Thus, the C-30 absolute configuration of the lavandulyl group in 4 is established as S. Moreover, compound 4 was determined and named as garcoblone D.The molecular formula of compound 5 was established to be C 38 H 50 O 7 from its HR-ESI-MS data (m/z 619.3633 [M + H] + , calcd for C 38 H 51 O 7 , 619.3629).…”

Stereodivergent Strategy in Structural Determination: Asymmetric Total Synthesis of Garcinol, Cambogin, and Related Analogues

“…Previously, their structures and relative configuration were identified by comparing the spectroscopic data with those of 1 . Recently, it was found that their structures were misassigned, and they were revised by our group via spectroscopic analysis . Because considerable research has been conducted based on 4 and 5 , their structures should be further confirmed by synthesis before related research can be accordingly corrected.…”

“…Recently, it was found that their structures were misassigned, and they were revised by our group via spectroscopic analysis. 18 Because considerable research has been conducted based on 4 and 5, their structures should be further confirmed by synthesis before related research can be accordingly corrected. The other two PPAPs, garcimultiflorone K 19 (3) and 13,14-didehydroxyisogarcinol (6, 13,14-DDHIG), 20 which demonstrated antiangiogenic activity 19,21 and anti-inflammatory activity, 20 (Scheme 1A), were configurationally identified by electronic circular dichroism (ECD).…”

“…The NMR spectra and specific rotation of 4 differed significantly from those reported for the natural guttiferone F, confirming the misassignment of its original structure. 16,18 The chemical shifts in 13 C NMR with major deviations (Δδ > 0.3) between the proposed guttiferone F and 4 were calculated. As shown in Scheme 4B, these carbons are mostly around the C-30 stereocenter (see Table S3′ for details), which implied that the stereochemistry of C-30 in the proposed guttiferone F was incorrect.…”