Total Synthesis of (+)-Haperforin G

Abstract

A concise chemical synthesis of (+)-haperforin G in 20 steps from commercially available starting materials is achieved with the integration of the Co-catalyzed intramolecular Pauson−Khand reaction for the stereoselective construction of cyclopentanone bearing an all-carbon quaternary stereogenic center at the bridge-head position and the light-initiated photocatalysis for convergent and asymmetric cross-coupling of the unstabilized C(sp 3 )-radical with an enone. The developed chemistry paves the way to synthesizing structurally diverse analogs of haperforin G (6).

Navigating the Pauson–Khand Reaction in Total Syntheses of Complex Natural Products

“…Finally, taking advantage of the presence of a hydroxyl group at C-6, reaction of 87 with SOCl 2 / pyridine produced a cyclic sulfite, which was then treated with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give 9 in 50% overall yield. The 1 H and 13 C NMR spectra and specific rotation of the synthesized 9 were in agreement with those reported in the literature, 4 and its structure has been confirmed by X-ray crystallographic analysis. The asymmetric total synthesis of 9 was therefore achieved in 20 steps, which included a concise Cocatalyzed PK reaction and a convergent photoredox catalysis as key steps.…”

“…The structure of 30 was confirmed by X-ray crystallographic analysis. Diastereoselective hydrogenation of 31 was achieved via an intramolecular [1,4]-HAT reaction by treatment with Fe(acac) 3 as a catalyst in the presence of PhSiH 3 . 33 The desired product 32 was obtained in 75% yield as a single diastereoisomer.…”

“…When this reaction was performed in deuterated ethanol (CD 3 CD 2 OD), product 31B was isolated in 75% yield and deuterium atoms were distributed between C3 (29% D) and C1 (17% D) (D/H ≈ 1/3 in total). This indicated that the radical-based reduction could occur by abstractions of protons from both C1 and C3 carbons via [1,4]-and [1,5]-HAT processes. On the other hand, when ketal 31C, in which the protons at C1 and C3 position are less activated compared with ketone 31, was used as the substrate, 31E-iso bearing an opposite stereochemistry at C9 was obtained in 70% yield, together with its isomer 31D in 9% yield.…”

Enhanced high voltage performance of LiNi0.5Mn0.3Co0.2O2 cathode via the synergistic effect of LiPO2F2 and FEC in fluorinated electrolyte for lithium-ion batteries

“…The straight line in the low-frequency region is ascribed to the Warburg impedance ( W 1 , relating to Li + diffusion within the electrode). 37–39 It was noted that the semicircles of samples increased continuously with cycling at high-medium frequency, which was ascribed to the progressive growth of SEI on the cathode surface and the increased thickness of the SEI film caused by the electrolyte decomposition. Both resistances, R sei and R ct , increased from the 1st to the 150th cycle in the following order: LiPO 2 F 2 -containing FEC-based electrolyte < FEC-based electrolyte < EC-based electrolyte.…”

Aglatestine A, a Rearranged Limonoid with a 3/6/6 Tricarbocyclic Framework from the Fruits of Aglaia edulis

“…Limonoids have attracted extensive attentions in the field of chemistry and biology due to various skeletons and broad-spectrum biological characteristics mainly in antifeedant, cytotoxic, and anti-inflammatory activities . Diverse C–C bond cleavages, rearrangement, and decarbonization on the skeleton lead to reports of plenty of novel limonoid derivatives in the past years, which also attracted many attentions from organic chemists to construct their diverse and complex carbocyclic limonoid scaffolds. , In this decade, we reported a large number of limonoids from genus Aphanamixis, Trichilia, Toona, and Chukrasia of the Meliaceae family. However, only one limonoid was reported in the Aglaia genus which encouraged us to search for various novel and biological limonoids in the Aglaia genus.…”