scholarly journals Asymmetric Total Synthesis of Crotophorbolone: Construction of the 5/7/6-Fused Ring System via an α-Alkoxy Bridgehead Radical Reaction

2016 ◽  
Vol 89 (10) ◽  
pp. 1137-1144 ◽  
Author(s):  
Daisuke Urabe ◽  
Taro Asaba ◽  
Masayuki Inoue
Keyword(s):  
Total Synthesis ◽  
Radical Reaction ◽  
Ring System ◽  
Asymmetric Total Synthesis ◽  
Fused Ring ◽  
Fused Ring System

Total Synthesis of the Diterpenoid Alkaloid Arcutinidine Using a Strategy Inspired by Chemical Network Analysis

2019 ◽  
Author(s):  
Kyle Owens ◽  
Shelby McCowen ◽  
Katherine Blackford ◽  
Sohei Ueno ◽  
Yasuo Hirooka ◽  
...  
Keyword(s):  
Natural Products ◽  
Network Analysis ◽  
Total Synthesis ◽  
Ring System ◽  
Diels Alder ◽  
Diterpenoid Alkaloids ◽  
Oxidative Dearomatization ◽  
Diterpenoid Alkaloid ◽  
Fused Ring ◽  
Fused Ring System

Arcutinidine and other arcutinidine-type diterpenoid alkaloids feature an intricate polycyclic, bridged framework with unusual connectivity. A chemical network analysis approach to the arcutane skeleton enabled the identification of highly simplifying retrosynthetic disconnections, which indicated that the caged structure could arise from a simpler fused ring system. On this basis, a total synthesis of arcutinidine is reported herein, featuring an unprecedented oxopyrrolium Diels–Alder cycloaddition which furnishes a key tetracyclic intermediate. In addition, the synthesis utilizes a diastereoselective oxidative dearomatization/cycloaddition sequence and a SmI2-mediated C–C coupling to forge the bridged framework of the natural products. This synthetic plan may also enable future investigations into the biosynthetic relationships between the arcutanes, the related diterpenoid atropurpuran, and other diterpenoid alkaloids.

Total Synthesis of the Diterpenoid Alkaloid Arcutinidine Using a Strategy Inspired by Chemical Network Analysis

2019 ◽  
Author(s):  
Kyle Owens ◽  
Shelby McCowen ◽  
Katherine Blackford ◽  
Sohei Ueno ◽  
Yasuo Hirooka ◽  
...  
Keyword(s):  
Natural Products ◽  
Network Analysis ◽  
Total Synthesis ◽  
Ring System ◽  
Diels Alder ◽  
Diterpenoid Alkaloids ◽  
Oxidative Dearomatization ◽  
Diterpenoid Alkaloid ◽  
Fused Ring ◽  
Fused Ring System

Arcutinidine and other arcutinidine-type diterpenoid alkaloids feature an intricate polycyclic, bridged framework with unusual connectivity. A chemical network analysis approach to the arcutane skeleton enabled the identification of highly simplifying retrosynthetic disconnections, which indicated that the caged structure could arise from a simpler fused ring system. On this basis, a total synthesis of arcutinidine is reported herein, featuring an unprecedented oxopyrrolium Diels–Alder cycloaddition which furnishes a key tetracyclic intermediate. In addition, the synthesis utilizes a diastereoselective oxidative dearomatization/cycloaddition sequence and a SmI2-mediated C–C coupling to forge the bridged framework of the natural products. This synthetic plan may also enable future investigations into the biosynthetic relationships between the arcutanes, the related diterpenoid atropurpuran, and other diterpenoid alkaloids.

scholarly journals NEW ROUTES TO 1,2-DIAZOLES WITH A FUSED RING SYSTEM BY REDUCTIVE AND OXIDATIVE CYCLIZATIONS

1974 ◽  
Vol 3 (9) ◽  
pp. 951-954 ◽  
Author(s):  
Joung Hee Lee ◽  
Akira Matsumoto ◽  
Masayuki Yoshida ◽  
Osamu Simamura
Keyword(s):  
Ring System ◽  
Oxidative Cyclizations ◽  
Fused Ring ◽  
Fused Ring System

Regiospecific preparation of 10-allyl-1-ketoquinolizidine and an unexpected disproportionation during its Wolff–Kischner reduction

1979 ◽  
Vol 57 (16) ◽  
pp. 2114-2117 ◽  
Author(s):  
John M. McIntosh
Keyword(s):  
Ring System ◽  
Sigmatropic Rearrangement ◽  
High Yield ◽  
Reaction Conditions ◽  
Fused Ring ◽  
Fused Ring System

Regiospecific formation of 10-allyl-1-ketoquinolizidine (7) is achieved in high yield by a [2.3] sigmatropic rearrangement of N-allyl-1-ketoquinolizidinium bromide (6). Wolff–Kischner reduction of 7 affords 10-allylquinolizidine (8) contaminated by the 10-propyl and 10-ethynyl analogs in amounts which depend on the reaction conditions. The carbon-13 spectrum of 8 indicates a trans-fused ring system with an axial substituent at C-10.

scholarly journals Bioactive Compounds from Euphorbia usambarica Pax. with HIV-1 Latency Reversal Activity

2021 ◽  
Vol 14 (7) ◽  
pp. 653
Author(s):  
Yu-Chi Tsai ◽  
Racheal A. Nell ◽  
Jonathan E. Buckendorf ◽  
Norbert Kúsz ◽  
Peter Waweru Mwangi ◽  
...  
Keyword(s):  
Antiretroviral Therapy ◽  
Lactone Ring ◽  
Ring System ◽  
Primary Mechanism ◽  
Fused Ring ◽  
Cd69 Expression ◽  
K 13 ◽  
Latent Hiv ◽  
Fused Ring System ◽  
Hiv 1

Euphorbia usambarica is a traditional medicine used for gynecologic, endocrine, and urogenital illnesses in East Africa; however, its constituents and bioactivities have not been investigated. A variety of compounds isolated from Euphorbia species have been shown to have activity against latent HIV-1, the major source of HIV-1 persistence despite antiretroviral therapy. We performed bioactivity-guided isolation to identify 15 new diterpenoids (1–9, 14–17, 19, and 20) along with 16 known compounds from E. usambarica with HIV-1 latency reversal activity. Euphordraculoate C (1) exhibits a rare 6/6/3-fused ring system with a 2-methyl-2-cyclopentenone moiety. Usambariphanes A (2) and B (3) display an unusual lactone ring constructed between C-17 and C-2 in the jatrophane structure. 4β-Crotignoid K (14) revealed a 250-fold improvement in latency reversal activity compared to crotignoid K (13), identifying that configuration at the C-4 of tigliane diterpenoids is critical to HIV-1 latency reversal activity. The primary mechanism of the active diterpenoids 12–14 and 21 for the HIV-1 latency reversal activity was activation of PKC, while lignans 26 and 27 that did not increase CD69 expression, suggesting a non-PKC mechanism. Accordingly, natural constituents from E. usambarica have the potential to contribute to the development of HIV-1 eradication strategies.

scholarly journals 1-Benzyl-5-bromoindoline-2,3-dione

IUCrData ◽  
2016 ◽  
Vol 1 (4) ◽  
Author(s):  
Yassine Kharbach ◽  
Youssef Kandri Rodi ◽  
Catherine Renard ◽  
El Mokhtar Essassi ◽  
Lahcen El Ammari
Keyword(s):  
Hydrogen Bonds ◽  
Ring System ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
Compound C ◽  
Centroid Distance ◽  
Fused Ring ◽  
Common Plane ◽  
The Mean ◽  
Fused Ring System

In the title compound, C15H10BrNO2, the indoline ring system, the two ketone O atoms and the Br atom lie in a common plane, with the largest deviation from the mean plane being 0.073 (1) Å for the Br atom. The fused-ring system is nearly perpendicular to the benzyl ring, as indicated by the dihedral angle between them of 74.58 (10)°. In the crystal, molecules are linked by weak C—H...O hydrogen bonds and by π–π interactions [inter-centroid distance = 3.625 (2) Å], forming a two-dimensional structure.

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