On terpenes. LVIII. Total synthesis of 1,1,4,8-tetramethylcycloundecane: Proof of the eleven-membered ring in humulene

1954 ◽  
Vol 19 (3) ◽  
pp. 570-580 ◽  
Author(s):  
F. Šorm ◽  
M. Streibl ◽  
V. Jarolím ◽  
L. Novotný ◽  
L. Dolejš ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Membered Ring

Convergent Total Synthesis of Principinol D, a Rearranged Kaurane Diterpenoid

2019 ◽  
Author(s):  
Timothy Newhouse ◽  
Aneta Turlik ◽  
Yifeng Chen ◽  
Anthony Scruse
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Late Stage ◽  
Membered Ring ◽  
Entry Point ◽  
Ketone Reduction ◽  
Coupling Approach

<div> <p>The total synthesis of principinol D, a rearranged kaurane diterpenoid, is reported. This grayanane natural product is constructed via a convergent fragment coupling approach, wherein the central 7-membered ring is synthesized at a late stage. The bicyclo[3.2.1]octane fragment is accessed by a Ni-catalyzed α-vinylation reaction. Strategic reductions include a diastereoselective SmI<sub>2</sub>-mediated ketone reduction with PhSH and a new protocol for selective ester reduction in the presence of ketones. The convergent strategy reported herein may be an entry point to the larger class of kaurane diterpenoids.</p> </div>

Towards the Total Synthesis of Schisandrene: Stereoselective Synthesis of the Dibenzocyclooctadiene Lignan Core

Synlett ◽  
2018 ◽  
Vol 29 (07) ◽  
pp. 908-911 ◽  
Author(s):  
K. Babu ◽  
Arramshetti Venkanna ◽  
Borra Poornima ◽  
Bandi Siva ◽  
B. Babu
Keyword(s):  
Total Synthesis ◽  
Stereoselective Synthesis ◽  
Asymmetric Reduction ◽  
Cross Coupling ◽  
Membered Ring ◽  
Stille Reaction ◽  
Reaction Sequence ◽  
Ring Closing Metathesis ◽  
Synthetic Strategy ◽  
First Time

A stereoselective synthesis of the dibenzocyclooctadiene ­lignan core of the natural product schisandrene is described. Starting from readily available gallic acid, the synthetic strategy involves Suzuki–Miyaura cross-coupling, Stille reaction, and ring-closing metathesis (RCM) in the reaction sequence. The required asymmetric center at C-7′ was established by an asymmetric reduction of a keto compound using the Corey–Bakshi–Shibata (CBS) catalyst. In our approach, the eight-membered ring was achieved by RCM for the first time.

Studies on double acylation of aromatic hydrocarbons. XI. A total synthesis of 5,6-Dihydro-4H-benz[de]anthracene

1972 ◽  
Vol 25 (7) ◽  
pp. 1521 ◽  
Author(s):  
A Rahman ◽  
BM Vuano ◽  
NM Rodriguez
Keyword(s):  
Total Synthesis ◽  
Propionic Acid ◽  
Intramolecular Cyclization ◽  
Butyric Acid ◽  
Aromatic Hydrocarbons ◽  
Dibasic Acid ◽  
Membered Ring ◽  
Ring Closure ◽  
Partial Synthesis

Starting from ethyl 3-(1-naphthyl)propionate (1), the dibasic acid 4-(4-carboxy-ethyl-I-naphthyl)butyric acid (3) was prepared, which served as a key compound for the synthesis of 5,6-dihydro-4H-benz[de]anthraoene (6) by a double intramolecular cyclization. The monocyolization of the dibasic acid (3) gave rise by a preferential six-membered ring closure, to 3-(1-oxo-1,2,3,4-tetrahydro-9-phenanthryl)propionic acid (7). A partial synthesis of 5,6-dihydro-4H-benz[de]anthracene (6), by succinoylation of perinaphthane followed by usual synthetic steps, is reported as confirmatory evidence of the identity of (6) obtained by double cyclization of the diacid. Some aspects of the orientation of intramolecular acylation are discussed.

Five-membered ring annulation via thermal rearrangement of β-cyclopropyl α,β-unsaturated ketones. A formal total synthesis of the sesquiterpenoid (±)-zizaene

1982 ◽  
Vol 60 (23) ◽  
pp. 2965-2975 ◽  
Author(s):  
Edward Piers ◽  
Jacques Banville ◽  
Cheuk Kun Lau ◽  
Isao Nagakura
Keyword(s):  
Total Synthesis ◽  
Sodium Methoxide ◽  
Membered Ring ◽  
Yield Reduction ◽  
Thermal Rearrangement ◽  
Standard Methods ◽  
Unsaturated Ketones ◽  
Mild Conditions ◽  
Sodium Amalgam ◽  
High Yields

Treatment of the β-iodo enones 7–10 with lithium (phenylthio)(cyclopropyl)cuprate provided excellent yields of the corresponding β-cyclopropyl α,β-unsaturated ketones 11–14, respectively. When 3-isopropenyl-2-cyclohexen-1-one (16) was allowed to react with dimethyloxosulfonium methylide in dimethyl sulfoxide – tetrahydrofuran, 3-(1-methylcyclopropyl)-2-cyclohexen-1-one (17) was produced in 59% yield. Although thermal rearrangement (~425–450 °C) of compounds 11 and 17 produced high yields of the annulation products 19 and 22, respectively, similar reactions involving the β-cyclopropyl enones 12 and 13 were not efficient in terms of production of the corresponding bicyclic systems (23, 26, and/or 27, respectively). In these cases, predominant (24 + 25 from 12) or significant (28 + 29 from 13) amounts of monocyclic dienones were formed. The annulation product 22 served as a convenient starting material for a new formal total synthesis of the sesquiterpenoid (±)-zizaene (30). Conjugate addition of lithium divinylcuprate to 22 afforded the ketone 36 which was converted by standard methods (via 38 and 39) into the enone 40. Treatment of the latter substance with thiophenol in the presence of tetra-n-butylammonium fluoride gave 41, which was transformed via ketalization (41 → 42), hydroboration(42 → 43), tosylation (43 → 44), and oxidation (44 → 45) into the sulfone 45. When the latter compound was treated with potassium tert-butoxide in hexamethylphosphoramide, the tricyclic ketal sulfone 46 was produced in 85% yield. Reduction of 46 with sodium amalgam afforded the ketal 47, which upon hydrolysis under mild conditions gave the ketone 32. Treatment of the latter substance with sodium methoxide in methanol provided a 1:2 mixture of the epimeric ketones 31 and 32, which had been converted previously by Coates and Sowerby into (±)-zizaene (30).

scholarly journals Convergent Total Synthesis of Principinol D, a Rearranged Kaurane Diterpenoid

2019 ◽  
Author(s):  
Timothy Newhouse ◽  
Aneta Turlik ◽  
Yifeng Chen ◽  
Anthony Scruse
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Late Stage ◽  
Membered Ring ◽  
Entry Point ◽  
Ketone Reduction ◽  
Coupling Approach

<div> <p>The total synthesis of principinol D, a rearranged kaurane diterpenoid, is reported. This grayanane natural product is constructed via a convergent fragment coupling approach, wherein the central 7-membered ring is synthesized at a late stage. The bicyclo[3.2.1]octane fragment is accessed by a Ni-catalyzed α-vinylation reaction. Strategic reductions include a diastereoselective SmI<sub>2</sub>-mediated ketone reduction with PhSH and a new protocol for selective ester reduction in the presence of ketones. The convergent strategy reported herein may be an entry point to the larger class of kaurane diterpenoids.</p> </div>

Convergent Total Synthesis of (–)-Principinol D, a Rearranged Kaurane Diterpenoid

2019 ◽  
Author(s):  
Aneta Turlik ◽  
Yifeng Chen ◽  
Anthony Scruse ◽  
Timothy Newhouse
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Late Stage ◽  
Membered Ring ◽  
Entry Point ◽  
Ketone Reduction ◽  
Wide Range ◽  
Coupling Approach

<div> <p>The total synthesis of principinol D, a rearranged kaurane diterpenoid, is reported. This grayanane natural product was constructed via a convergent fragment coupling approach, wherein the central 7-membered ring was synthesized at a late stage. The <a>bicyclo</a>[3.2.1]octane fragment is accessed by a Ni-catalyzed α-vinylation reaction, followed by a diastereoselective SmI<sub>2</sub>-mediated ketone reduction. The convergent strategy reported herein may be an entry point to a wide range of kaurane diterpenoids. </p> </div>

scholarly journals A Concise Total Synthesis of (±)-Asteriscunolide C

Synlett ◽  
2013 ◽  
Vol 24 (20) ◽  
pp. e8-e8
Author(s):  
Rodney A. Fernandes ◽  
Vijay P. Chavan
Keyword(s):  
Total Synthesis ◽  
Membered Ring

This Letter has been retracted by the authors upon request of the Editorial Board for reasons of significant content overlap with a parallel submission to another journal.1 The Editorial Board recognizes that, had the submission to Chem. Commun. (submitted five weeks prior to this Synlett manuscript), been referenced and its contents disclosed, the striking similarities between the chiral (Chem. Commun.) and racemic (Synlett) syntheses would have been noted and the Synlett Letter would not have been accepted for publication. (1) A 12-membered to a strained 11-membered ring: first stereoselective total synthesis of (−)-asteriscunolide C, Fernandes, R. A.; Chavan, V. P. Chem. Commun. 2013, 49, 3354.

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