Synthesis of 8,14-Secosteroids from (S)-(+)-Carvone

2000 ◽  
Vol 65 (7) ◽  
pp. 1173-1182 ◽  
Author(s):  
Anna I. Kotyatkina ◽  
Vladimir N. Zhabinskii ◽  
Vladimir A. Khripach ◽  
Aede de Groot
Keyword(s):  
Total Synthesis ◽  
Membered Ring ◽  
Reductive Cleavage ◽  
Nitrile Oxide ◽  
Side Chain ◽  
Ene Reaction ◽  
Nitrile Oxides ◽  
Cyclic Enones ◽  
Derivatives Of ◽  
Ab Ring

A total synthesis of functionalised 8,14-seco steroids with five- and six-membered D rings is described. The synthesis is based on the transformation of (S)-carvone into a steroidal AB ring moiety with a side chain at C-9 that allowed the creation of a nitrile oxide at this position. The nitrile oxides were coupled with cyclic enones or enol derivatives of 1,3-diketones, and reductive cleavage of the obtained cycloadducts gave the desired products. The formation of a twelve-membered ring compound was observed in cycloaddition of one of the nitrile oxides with cyclopentenone as the result of an intramolecular ene-reaction followed by retroaldol reaction.

scholarly journals Synthesis and Antimicrobial Evaluation of Side-Chain Derivatives based on Eurotiumide A

Marine Drugs ◽  
2020 ◽  
Vol 18 (2) ◽  
pp. 92
Author(s):  
Nakayama ◽  
Sato ◽  
Nakamura ◽  
Hamada ◽  
Nagano ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Iodine Atom ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Antimicrobial Activities ◽  
Side Chain ◽  
Negative Bacterium ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Antimicrobial Evaluation ◽  
Derivatives Of

Side-chain derivatives of eurotiumide A, a dihydroisochroman-type natural product, have been synthesized and their antimicrobial activities described. Sixteen derivatives were synthesized from a key intermediate of the total synthesis of eurotiumide A, and their antimicrobial activities against two Gram-positive bacteria, methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA), and a Gram-negative bacterium, Porphyromonas gingivalis, were evaluated. The results showed that derivatives having an iodine atom on their aromatic ring instead of the prenyl moiety displayed better antimicrobial activity than eurotiumide A against MSSA and P. gingivalis. Moreover, we discovered that a derivative with an isopentyl side chain, which is a hydrogenated product of eurotiumide A, is the strongest antimicrobial agent against all three strains, including MRSA.

Organic Curing Agents for Polysulfide Sealants. III. A Mechanistic Interpretation of the Thermal Degradation of Nitrile Oxide-Cured Polysulfide Sealants

1990 ◽  
Vol 43 (1) ◽  
pp. 109 ◽  
Author(s):  
BC Ennis ◽  
PJ Hanhela ◽  
DB Paul
Keyword(s):  
Thermal Analysis ◽  
Acid Group ◽  
Spectroscopic Studies ◽  
Nitrile Oxide ◽  
Side Chain ◽  
Polymer Backbone ◽  
Nitrile Oxides ◽  
Liquid Polymers ◽  
Curing Agents ◽  
Group B

Sealants obtained by cure of polysulfide liquid polymers with aryl bis ( nitrile oxides) possess the thiohydroximic acid ester structural feature. Unexpectedly these materials were found to exhibit poor thermal stability: when heated at 60° they soften within days and liquefy in 3 weeks. Products obtained with excess nitrile oxide degraded faster than those produced with equimolar amounts of reagents. Interpretations considered included (A) dissociation of the thiohydroximic acid group, (B) reaction between nitrile oxide and a reactive centre in the polysulfide structure, and (c) addition of nitrile oxide to the side chain. It was shown that neither of the first two possibilities was applicable. Moreover, spectroscopic studies demonstrated that, after an initial rapid addition between nitrile oxide and thiol , a second slower reaction occurred which consumed additional nitrile oxide. Although aldehyde oximes and a- chloro oximes do not participate in such processes unless catalysts are present, thiohydroximic acid derivatives were shown to react with nitrile oxides at ambient temperature to form 1,2,4-oxadiazole 4-oxides and alkyl thiol . For the case of a polysulfide sealant the equivalent rupture of a C-S bond to form the thiol involves cleavage of the polymer backbone. Continuation of the process would lead to degradation of the sealant. These observations were supported by thermal analysis studies on the polysulfide sealants and model polymers.

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>

Therapeutic Journey of 5-Pyrazolones as a Versatile Scaffold: A Review

2021 ◽  
Vol 21 ◽  
Author(s):  
Ravinder Sharma ◽  
Pooja A. Chawla ◽  
Viney Chawla ◽  
Rajeev Verma ◽  
Nandita Nawal ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Protease Inhibitor ◽  
Medicinal Chemistry ◽  
Membered Ring ◽  
Present Review ◽  
Biological Profile ◽  
3C Protease ◽  
Structure Activity ◽  
Derivatives Of ◽  
Heterocyclic Moiety

Abstract: A sizeable proportion of currently marketed drugs come from heterocycles. The heterocyclic moiety 5-pyrazolone is well known five membered ring containing nitrogen. Derivatives of this wonder nucleus have exhibited activities as diverse as antimicrobial, anti-inflammatory, analgesic, antidepressant, anticonvulsant, antidiabetic, antihyperlipidemic, antiviral, antitubercular, antioxidant, anticancer and antiviral including action against severe acute respiratory syndrome (SARS) or 3C protease inhibitor. A number of drugs based on this motif have already made it to the market. Standard texts and literature on medicinal chemistry cite different approaches for the synthesis of 5-pyrazolones. The present review provides an insight view to 5-pyrazolone synthesis, their biological profile and structure activity relationship studies.

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

Absolute configuration at C(20) of the derivatives of 21-nor-5α-cholane-20,24-diol

1980 ◽  
Vol 45 (9) ◽  
pp. 2443-2451
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Side Chain ◽  
Chemical Correlation ◽  
The Absolute ◽  
Derivatives Of

Derivatives of 21-nor-5α-cholane-20,24-diol XI and XIX were prepared by stepwise construction of the side-chain in the position 17β. Their absolute configuration at C(20) was determined on the basis of chemical correlation with the derivatives of 21-nor-5α-cholan-20-ol, XVI and XXIV. The absolute configuration of alcohols XVI and XXIV was determined from the ratio of the yields in which they are formed during the reduction of ketone X and using the benzoate rule. To compounds XI-XVIII the configuration 20R and to compounds XIX-XXVI the configuration 20S has been assigned.

Sign in / Sign up

Export Citation Format

Share Document